UC-NRLF - UNITED STATES DEPARTMENT 0F AGRICULTURE BULLETIN No. 772 Contribution from the Bureau of Plant Industry WM. A. TAYLOR, Chief Washington, D. C. PROFESSIONAL PAPER March 20, 1920 THE GENERA OF GRASSES OF THE UNITED STATES WITH SPECIAL REFERENCE TO THE ECONOMIC SPECIES By A. S. HITCHCOCK. Systematic Agrostologist CONTENTS Page Scope and Plan of the Work ..... 1 Poaceae, the Grass Family ...... 5 Descriptions of the Subfamilies and Keys to the Tribes .......... 6 Descriptions of the Tribes and Keys to the Genera ........... Descriptions of the Genera 1. Bamboseae, the Bamboo Tribe 2. Festuceae, the Fescue Tribe . 3. Hordeae, the Barley Tribe .. 4. Aveneae, the Oat Tribe ..... 106 5. Agrostideae, the Timothy Tribe . . 121 6. Nazieae ^he Curly-Mesquite Tribr 165 Paeg Descriptions of the Genera Continued. 7. Chlorideae, the Grama Tribe ... 171 8. Phalarideae, the Canary-Grass Tribe 199 9: Oryzeae, the Rice Tribe 204 10. Zizanieae, the Indian-Rice Tribe . 206 11. Melinideae, the Molasses - Grass Tribe 212 12. Paniceae, the Millet Tribe . . . .213 13. Andropogoneae, the Sorghum Tribe 252 14. Tripsaceae, the Corn Tribe .... 280 List of New Species and New Names . .288 Index 289 WASHINGTON GOVERNMENT PRINTING OFFICE 1920 UNITED STATES DEPARTMENT OF AGRICULTURE ^^ BULLETIN No. 772 Contribution from the Bureau of Plant Industry WM. A. TAYLOR, Chief Washington, D. C. PROFESSIONAL PAPER March 20, 1920 THE GENERA OF GRASSES OF THE UNITED STATES, WITH SPECIAL REFERENCE TO THE ECONOMIC SPECIES. By A. S. HITCHCOCK, Systematic Agrostologist. CONTENTS. Page. Scope and plan of the work 1 Poaceae, the grass family 5 Descriptions of the subfamilies and keys to the tribes 6 Descriptions of the tribes and keys to the genera 8 Descriptions of the genera 22 1. Bamboscae, the bamboo tribe 22 2. Festuceae, the fescue tribe 24 3. Hordeae, the barley tribe 87 4. Aveneae, the oat tribe 106 5 Agrostideae, the timothy tribe 121 Page. Descriptions of the genera Continued. 6. Nazieae, the curly-mesquite tribe 1G5 7. Chlorideae, the grama tribe 171 8. Phalarideae, the canary-grass tribe ... 1C9 9. Oryzeae, the rice tribe 201 10. Zizanieae, the Indian-rice tribe 206 11. Mclinideae, the molasses-grass tribe . . 212 12. Paniceae, the millet tribe 213 13. Andropogoneae, the sorghum tribe... 252 14. Tripsaceae, the corn tribe 280 List of new species and new names 288 Index ... 289 SCOPE AND PLAN OF THE WORK. The present bulletin describes all the genera of grasses that include species that are native, have been introduced, or are cultivated in the United States. Under each genus are given the species that are of economic importance, either as useful or harmful grasses. Of all grasses the grains are of the greatest importance. Chief among other useful grasses are those that are cultivated for meadow or pasture and those indigenous species which furnish forage upon the native pasture or ranges. Other important grasses are the sugar-producing species, those used in broom or paper making, and the ornamental species. It is intended to give under each genus the botanical information concerning all our grasses that are conspicuous enough to have at- tracted the attention of agriculturists. The keys to the tribes and 97700 Bull. 77220 1 2 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. genera should enable- the user to identify the genera of all our grasses^ and the text under each genus should enable him to determine the species of our economic grasses. Under each genus are given the type * and the synonyms based upon American species, or the names that have been used in an American publication. The following generic names, of which the types have not been found, are based on American material but are unidentifiable from the descriptions: Anthipsimus Raf., Journ. de Phys. 89: 105, 1819. 2 Based on A. gonopodus Raf., " Dry hills of the Ohio." Dactylograrama Link, Hort. Berol. 2 : 248. 1833. Based on D. cimwides Link, described from garden specimens grown from seed from western North America. Flexularia Raf., Journ. de Phys. 89: 105. 1819. Based on F. comprcssa Raf., "Kentucky and Ohio." The tribes have been arranged in a new sequence based on the com- plexity of the flower structure, the most primitive being placed first and the most highly developed last. It is impossible to arrange them in a lineal sequence and at the same time represent their relationships, as the phylogenetic development has not been along a single line. The present arrangement is the closest approximation to natural re- lationships that can be shown in sequence. The highest development in any given tribe may be far more complex than the most primitive example of the tribe placed above it, but the relative development of each tribe is believed to be fairly represented by its position in the sequence. The bamboos are placed lowest, as certain genera, such as Arundinaria, show the least differentiation in the floral structure. The Andropogoneae and Tripsaceae are highly specialized, as is shown by the great diversity and complexity of the floral structures. The tribe Oryzeae of most authors includes two groups of diverse genera, each worthy of tribal rank. The allies of rice (Oryza) are here 1 The type species of a genus is the species or one of the species the author had chiefly in mind when describing the genus. Most authors of to-day designate the type species, but earlier authors usually did not. To make the application of generic names more cer- tain, old genera are now put on a type basis ; that is, one of the original species is chosen as the type. If, then, a genus as originally established included species belonging in two or more genera the name of the genus goes with the type species and the species related to it. It will be seen that the type species of a genus as here given often bears a differ- ent generic name. (See Miegia, based on Arundinaria macrosperma, p. 22, and Panicu- laria, based on Poa aquatica, p. 34.) This means that the genus was based on a species previously described under a different genus. In this work the type species is given for all generic names, whether valid or synonyms. The reasons for selecting a certain species as the type are given in each case. Among several species, the one most familiar to the au- thor of the genus may be selected as the type. Species described by Linnaeus in his flora of Sweden (Flora Suecica) and in his flora of Lapland (Flora Lapponica) were familiar to him and are often the types of his genera. (For a further discussion of types, see Hitchcock, Generic Types with Special Reference to the Grasses of the United States, Amer. Journ. Bot. 5 : 248-253, May, 1918 ; and Report of the Committee on Generic Types of the Botanical Society of America, Science, n. ser. 49: 333-336, Apr. 4, 1919.) 2 The form for literature citations throughout this bulletin is in the main that used in publications of the United States National Herbarium. GENERA OF GRASSES OF THE UNITED STATES. 6 retained in the tribe Oryzeae, while the allies of Indian rice (Zizania) have been segregated as the tribe Zizanieae. Several genera referred to Oryzeae in current works on the classification of the grasses but not represented in the United States are evidently not closely allied to either tribe. Their disposition is deferred, pending further study. The tribe Nazieae (Zoysieae) also is composed of diverse genera. Hilaria and Aegopogon should be segregated from Nazia, Anthe- phora, and their allies. They are more closely related to certain of the Chlorideae, such as Bouteloua and Cathestecum. For the present- they are appended to the Nazieae, as their final disposition must await a careful comparison with several genera outside our geographical limits. One species of each genus is illustrated. ' A few of the larger genera are represented by more than one illustration, especially if the habit of the species shows considerable diversity. The chief figure of each illustration shows the habit of the plant, and the ac- cessory figures show the structure of the spikelets and florets. The habit drawings are usually half natural size; the details of the spikelet are enlarged from 2 to 20 times. The parts of the spikelet shown are selected to indicate generic differences and are not uni- formly of comparable parts, though there is always a figure of a spikelet and generally of a floret. The habit drawings are by Mary Wright Gill, and the details of the spikelet are by Agnes Chase. There are in the United States about 1,500 species of grasses. Of these about 60 are cultivated. Approximately 140 native species are important forage grasses and are constituents of our stock ranges or of wild prairie hay. Many others are occasionally eaten by stock but are not sufficiently abundant to be included among our economic grasses. About 60 species are w r eeds introduced from foreign coun- tries, chiefly from Europe. In this bulletin the word grass is used in its botanical sense, that is, as applying only to plants of the natural family Poaceae (or Gramineae). Many plants other than grasses are used for forage, among such the clovers, alfalfa, vetches, peas, beans, and other leguminous species being the most important. Sedges and rushes resemble grasses but belong to distinct plant families. The rushes (Juncaceae) are distinguished by having small green flowers with a 6-parted perianth. The sedges (Cyperaceae) are distinguished from grasses by having 3-rankecl leaves. The stems are often 3-sided. The leaves of grasses are 2-ranked and the stems are never 3-sided. The flowers of sedges are small and greenish, like those of grasses, but there is no bract (palea) between the flower and the rachilla. Sedges and rushes usually inhabit wet places or marshes, . though some of them (such as the nut-grass, Cyperus rotundus} are weeds 4 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. in cultivated soil. They are usually of little importance as forage plants. The sedges and rushes are not included in this bulletin. The cultivated grasses may be classified according to their use as grains, forage grasses, sugar-producing grasses, textile grasses, soil binders, lawn grasses, and ornamental grasses. Grains are those grasses whose fruit or grain is used for food or for stock feed. The common grains are wheat, corn, oats, rye, bar- ley, rice, sorghum, and millet. The forage grasses are those used for meadows, pastures', soiling, and silage. Meadow grasses are those cut for hay. The chief meadow grasses of the United States are (1) in the cool humid region, timothy, red- top, orchard grass, and meadow fescue; (2) in the warm humid region, Bermuda grass, Johnson grass, and (in Florida) Natal grass: (3) in the dry area east of the Great Plains, millet and sorghum (including its varieties, such as kafir and Sudan grass) ; (4) in the northern part of the Great Plains, brome-grass ; (5) on the Pa- cific coast, wheat, oats, and barley for the production of grain hay. Wild hay is chiefly from three sources: (1) Prairie hay from the region lying just east of the Great Plains, including various native species such as big bluestem (Andropogon furcatm}* little bluestem (A. scoparius), Indian grass (Sorghastrum nutans), and switch- grass (Panicum virgatum) ; (2) fresh marsh hay from the region be- tween the Dakotas and Michigan, including chiefly bluejoint (Cala- magrostis canadensis) , reed canary grass (Phalams ammdinacea) , and slough-grass (Beckmannia erucaeformis) ; and (3) salt marsh hay used mostly for bedding and for packing, including usually salt- marsh grass (Spartina patens) and black-grass (a kind of rush, Juncus gerardi). Pasture grasses are those that furnish forage to grazing animals. The two most important cultivated pasture grasses of the United States are bluegrass in the Northern States and Bermuda grass in the South. The meadow grasses are also used for pasture, and in the Gulf States carpet grass is of some importance. The wild grasses used for grazing are commonly called range grasses. The most important are (1) on the Great Plains, buffalo grass, curly mesquite, and grama (Bouteloua grac'dis and B. hirsuta) ; (2) in the Southwest, several species of grama (Bouteloua), Hilaria, and Sporobolus airoides; (3) in the mountain regions, pine-grass, blue bunch-grass, and mountain bunch-grass (in Oregon) ; Arizona fescue (in northern Arizona) ; and the wheat-grasses (in the Rocky Mountains). Soiling grasses, those cut and fed green, include the common small grains, corn, and the sorghums, and (locally in the South) pearl millet and teosinte. GENERA OF GRASSES OF THE UNITED STATES. 5 Any forage grass may be preserved in a silo, but corn is the one most commonly used for this purpose. The most important lawn grasses are (1) in the North, bluegrass, Rhode Island bent, and creeping bent; (2) in the South, Bermuda grass, carpet grass, and St. Augustine grass. The ornamental grasses include the reeds, such as pampas grass and eulalia ; border grasses, such as fountain grass and blue fescue ; and variegated grasses, such as ribbon grass. Soil-binding grasses are species having vigorous rhizomes which hold sand or other loose soil and prevent erosion by water or wind. Banks are secured against water erosion by a covering of redtop or Bermuda grass. The most important sand binder in use in this coun- try is beach-grass (AimnophUa arenaria). This is planted upon sand dunes to prevent wind erosion. The two sugar-producing grasses are sugar cane and the saccha- rine varieties of sorghum. No textile grasses are cultivated in the United States. The esparto grasses (Spartina tenacissima and Lyyeum spartum) of Spain and Algeria furnish fiber for the manufacture of paper and cordage. All these grasses are mentioned in the text under the proper genus. (See index.) POACEAE, THE GRASS FAMILY. Flowers perfect (rarely unisexual), small, with no distinct peri- anth, arranged in spikelets consisting of a shortened axis (rachilla] and 2 to many 2-ranked bracts, the lowest two being empty (the glumes, rarely one or both .of these obsolete), the one or more succeed- ing ones (lemmas] bearing in their axils a single flower, and, between the flower and the rachilla, a second 2-nerved bract (the palea), the lemma, palea, and flower together constituting the floret; stamens 1 to 6, usually 3, -with very delicate filaments and 2-celled anthers; pistil 1, with a 1-celled 1-ovuled ovary, 2 (rarely 1 or 3) styles, and usually plumose stigmas; fruit a caryopsis with starchy endosperm and a small embryo at the base on the side opposite the hilum. Herbs, or rarely woody plants, with usually hollow stems (culms) closed at the nodes, and 2-ranked parallel-veined leaves^ these con- sisting of 2 parts, the sheath, enveloping the culm, its margins over- lapping or sometimes grown together, and the Made, usually flat; between the two on the inside, a membranaceous hyaline or hairy appendage (the liguZe) . The spikelets are almost always aggregated in spikes or panicles at the ends of the main culms or branches. The perianth is usually represented by 2 (rarely 3) small hyaline scales (the lodicules) at the base of the flower inside the lemma and palea. The grain or 6 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. cjiryopsis (the single seed and the adherent pericarp) may be free, as in wheat, or permanently inclosed in the lemma and palea. as in the oat. Rarely the seed is free from the pericarp, as in species of Sporobolus and Eleusine. The culms of bamboos are woody, as are also those of a few genera, such as Olyra and Lasiacis, belonging to other tribes. The culms are solid in our species of the tribes Trip- saceae and Andropogoneae. The margins of the sheaths are grown together in species of Bromus, Danthonia. Festuca, Melica, Panicu- laria, and other genera. The parts of the spikelet may be modified in various ways. The first glume, and more rarely also the second, may be wanting. The lemmas may contain no flower, or even no palea, or may be reduced or rudimentary. Rarely, as in species of Agrostis and Andropogon, the palea is obsolete. Most of the genera of grasses fall naturally into one of the two series or subfamilies. The remaining few are rather arbitrarily as- signed to one or the .other series. In the same manner, most of the genera may be assembled into distinct and w T ell-marked tribes, but several are not closely allied to the other genera in the tribe to which the} 7 are assigned but are so placed for convenience in classification. DESCRIPTIONS OF THE SUBFAMILIES AND KEYS TO THE TRIBES. SUBFAMILY 1, POATAE. Spikelets 1 to many flowered, the reduced florets, if any. above the perfect florets (except in Phalarideae ; sterile lemmas below as well as above in Campulosus, TJniola, and Blepharidachne) ; articulation usually above the glumes; spikelets usually more or less laterally compressed. Key to the t riles of Poatae. riiints woody, the culms perennial; spikelets several-flowered. 1. Bamboseae (p. 22). Plants herbaceous, the culms annual. Spikelets with 2 staminate, neuter, or rudimentary lemmas unlike and below the fertile lemma; no sterile or rudimentary rtoivts above 8. Phalarideae (p. 199). Spikelets without sterile lemmas below the perfect floret (or these rarely present and like the fertile -ones, a dissimilar pair below and a rudimentary floret above in Blepharidachue). Spikelets unisexual, articulate below the glumes, 1-flowered, terete or nearly so 10. Zizanieae (p. 200). Spikelets perfect (rarely unisexual but then not as above), usu- ally articulate above the glumes. Spikelets articulate below the glumes, 1-flowered, very flat, the lemma and palea about equal, both keeled; glumes small or wanting 9. Oryzeae (p. 204), GENERA OF GRASSES OF THE UNITED STATES. 7 Spikelets articulate above the glumes (rarely below, but the glumes, at least one, well developed). Spikelets 1-flowered in groups (short spikes) of 2 to 5 (single in Osterdamia), the groups racemose along a main axis, falling entire ; lemma and palea thin- ner than the glumes 6. Nazieae (p. 165). Spikelets not as above. Spikelets sessile on a usually continuous rachis (short-pedicellate in Leptochloa; the rachis disarticulating in Monerina, Phpliurus, Hor- deum, Sitanion, and a few species of allied genera). Spikelets on opposite sides of the rachis; spike terminal, single /. 3. Hordeae (p. 87). Spikelets on one side of the rachis ; spikes usu- ally more than 1, digitate or racemose. 7. Chlorideae (p. 171). Spikelets pedicellate in open or contracted, some- times spikelike, panicles (sessile and distant in Eragrostis sessilispica) . Spikelets 1-flowered 5. Agrostideae (p. 121). Spikelets 2 to many flowered. Glumes as long as the lowest floret, usually as long as the spikelet; lemmas awned from the back (spikelets awn- less in Koeleria and Sphenopholis). 4. Aveneae (p. 106). Glumes shorter than the first floret (except in Dissanthelium with ,long rachilla joints) ; lemmas awnless or awned from the tip or from a bifid apex. 2. Festuceae (p. 24). SUBFAMILY 2, PANICATAE. Spikelets with one perfect terminal floret (disregarding those of .ne few monoecious genera and the st animate and neuter spikelets) and a sterile or staminate floret below, usually represented by a sterile lemma only, one glume sometimes (rarely both glumes) wanting; articulation below the spikelets, either in the pedicel, in the rachis, or at the base of a cluster of spikelets, the spikelets falling entire, singly, in groups, or together with joints of the rachis; spikelets, or at least the fruits, more or less dorsally compressed. Key to the tribes of Pamcatae. Glumes membra naceous, the sterile lemma like the glumes in texture. Fertile lemma and palea thinner than the glumes; sterile lemma awned from the notched summit 11. Melinideae (p. 212). Fertile lemma and palea indurate or at least firmer than the glumes. 12. Paniceae (p. 213). Glumes indurate ; fertile lemma and palea hyaline or membranaceous, the sterile lemma (when present) like the fertile one in texture. Spikelets unisexual, the pistillate below, the staminate above, on the same inflorescence or in separate inflorescences. 14. Tripsaceae (p. 280). 8 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. Spikelets in pairs, one sessile and perfect, the other pedicellate and usually staminate or neuter (the pedicellate one sometimes obsolete, rarely both pedicellate) ; lemmas hyaline. 13. Andropogoneae (p. 1252). DESCRIPTIONS OF THE TRIBES AND KEYS TO THE GENERA. TRIBE 1, BAMBOSEAE. The tribe which includes the bamboos is for the most part confined to the Tropics and Subtropics. One genus extends into the southern United States. The bamboos have woody jointed, usually holloAV culms either erect or vinelike. Some of the larger kinds are as much as a foot in diameter and, 100 feet in height. The common economic species of the Tropics, such as Bambos vulgaris Schrad. (Banibos bambos (L.) Wight), because of the large hollow culms with hard partitions at the nodes found in most large species, can be used for a great variety of purposes. Many kinds of bamboos are cultivated for ornament in the warmer parts of the United States, especially in Florida and California. Arundinaria japonica Sieb. and Zucc. with several-flowered spikelets, and a few species of Phyl- lostachys, are hardy as far north as Washington. They form dense masses of shoots, usually 8 to 20 feet high. Phyllost achys does not usually flower in this country, but the plants can be distinguished by the internodes which are flattened on one side. Bambusa is a modi- fied spelling of the original Bambos. TRIBE 2, FESTUCEAE. Spikelets more than 1-flowered, usually several-flowered, in open, narrow, or sometimes spikelike panicles; lemmas awnless or awned from the tip, rarely from between the teeth of a bifid apex ; rachilla usually disarticulating above the glumes and between the florets. A large and important tribe, mainly inhabitants of the cooler regions. The lemma is divided into several awns in Pappophorum and its allies, is 'deeply 2-lobed In Triplasis and in a few species of Triodia, 3-lobed in Blepharidachne, several-toothed in Orcuttia, and slightly 2 -toothed in Bromus and a few other genera, the awn, when single, arising from between the teeth. The paleas are persistent upon the continuous rachilla in most species of Eragrostis. Sclero- pogon, Monanthochloe, Distichlis, and a few species of Poa and Eragrostis are dioecious. Gynerium, Cortaderia, Arundo, and Phrag- mites are tall reeds. In Blepharidachne there is a pair of sterile florets at the base of the single fertile floret, and a rudiment above. In some species of Melica there is, above the fertile florets, a club- shaped rudiment consisting of one or more sterile lemmas. In Uniola there arc one to four sterile lemmas below the fertile ones. In Melica imperfecta and M. torreyana there may be but one perfect floret. GENERA OF GRASSES OF THE UNITED STATES. Key to the genera of Festuceae. la. Plants dioecious, the sexes very dissimilar, the pistillate lemmas with 3 long twisted divergent awns, the staminate lemma awnless or mucronate 30. SCLEROPOGON. Ib. Plants with perfect flowers, or, if dioecious, the sexes not dissimilar in appearance 2 2a. Lemmas divided at the summit into 5 to several awns or awn- like lobes 3 ,>;i. Awnlike lobes 5 ; inflorescence a simple erect raceme. 29. ORCUTTIA. 3b. Awns 9 or more 4 4a. Awns unmixed with awned teeth ; all the florets falling attached, their awns forming a pappuslike crown, only the lowest floret fertile ; panicles narrow. 32. PAPPOPHOBUM. 4b. Awns mixed with awned teeth; florets not falling at- tached, the rachilla disarticulating between them; panicles somewhat open 31. COTTEA. 2b. Lemmas awnless, with a single awn, or, if 3, the lateral awns minute 5 5a. Tall stout reeds with large plumelike panicles; lemmas or rnchilla with long silky hairs as long as the lemmas G Ga. Lemmas hairy; rachilla naked 19. ARUNDO. Gb. Lemmas naked; rachilla hairy 20. PHRAGMITES. 5b. Low or rather tall grasses, rarely over 5 feet tall 7 7a. Plants dioecious, perennial; lemmas glabrous; grasses of salt or alkaline soils 8 8a. Plants low and creeping; spikelets obscure, scarcely differentiated from the short crowded rigid leaves 16. MONANTHOCHLOE. Sb. Plants erect from creeping rhizomes; spikelets in a narrow simple exserted panicle 17. DTSTICHLIS. 7b. Plants not dioecious (except in a few species of Poa with villous lemmas and in an annual species of Eragrostis) _ 9 9a. Spikelets of two forms, sterile and fertile intermixed ; panicle dense, somewhat one-sided 10 lOa. Fertile spikelets 2 or 3 flowered ; sterile spike- lets with numerous rigid awn-tipped glumes; panicle dense and spikelike 22. CYNOSTJRTTS. lOb. Fertile spikelets with 1 perfect floret, long- awned ; sterile spikelets with many obtuse glumes ; panicle branchlets short, nodding. 23. ACHYRODES. 9b. Spikelets all alike in the same inflorescence 11 lla. Lemmas 3-nerved, the nerves prominent, often hairy 12 12a. Inflorescence a few-flowered head or capi- tate panicle overtopped by the leaves or partly concealed in them ; lemmas toothed or cleft ; low plants of the arid regions, _ 13 13a. Inflorescence hidden among the sharp- pointed leaves, not woolly; plants annual (Chlorideae) 97. MUNROA. 13b. Inflorescence a capitate woolly panicle, not concealed ; plants perennial 14 10 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. Key to the genera of Festiweae Continued. 14a. Lemmas cleft either side of the midnerve to near the base, the lower two sterile, the third floret fertile, the fourth reduced to a 3-awned rudiment- 28. BLEPHABIDACHNE. 14b. Lemma 2-lobed but not deeply cleft, all fertile but the uppermost 26. TEIODIA. 12b. Inflorescence an exserted open or spikelike panicle 15 15a. Lemmas pubescent on the nerves or callus (except in Tri- *odia albescens), the midnerve usually exserted as an awn or mucro 16 16a. Nerves glabrous; callus densely hairy; lemmas firm; panicle large, diffuse 15. REDFIELDIA. 16b. Nerves hairy at least below, the lateral ones often conspicuously so 17 17a. Palea long-ciliate on the upper half 27. TRIPLASIS. 17b. Palea sometimes villous but not lorig-ciliate on the upper half; perennials 26. TEIODIA. 15b. Lemmas not pubescent on the nerves nor callus (the inter- nerves sometimes pubescent), awnless IS 18a. Glumes longer than the lemmas ; lateral nerves of lemma marginal, the internerves pubescent 14. DISSANTHELIUM. ISb. Glumes shorter than the lemmas; lateral nerves not marginal, the internerves glabrous 19 19a. Lemmas chartaceous; grain large and beaked, at maturity forcing the lemma and palea open_ 13. DIAEINA. 19b. Lemmas membranaceous ; if firm, the grain neither large nor beaked 20 20a. Spikelets subterete; palea longer than the lemma, bowed out below 12. MOLINIA. 20b. Spikelets compressed ; palea not longer than the lemma, not bowed out below 21 21a. Lemmas truncate ; spikelets 2-flowered. 11. CATABBOSA. 21b. Lemmas acute or acuminate; spikelets 3 to many flowered ; rachilla continuous, the paleas usually persistent after the fall of the lemmas 10. EEAGEOSTIS. 111). Lemmas 5 to many nerved, the nerves sometimes obscure 22 22a. Spikelets with 1 to 4 empty lemmas below the fertile florets; nerves obscure; lemmas firm 18. UNIOLA. 22b. Spikelets with no empty lemmas below the fertile florets ; nerves usually prominent; lemmas membranaceous (firm in a few species of Bromus and Festuca) 23 23a. Lemmas flabellate; glumes wanting; inflorescence dense, cylindric; low annual 25. ANTHOCHLOA. 23b. Lemmas not flabellate; glumes present; inflorescence not cylindric 24 24a. Palea winged on the lower half of the keels; spikelets linear, in a loose raceme 5. PLEUEOPOGON. 24b. Palea not winged on the lower half of the keels; in- florescence mostly paniculate 25 25a. Lemmas as broad as long, the margins outspread; florets closely imbricate, horizontally spreading- 9. BBIZA. 25b. Lemmas longer than broad, the margins clasping the palea ; florets not horizontally spreading 26 GENEKA OF GRASSES OF THE UNITED STATES. 11 Key to the genera of Festuceae Continued. 2Ga. Callus of florets bearded ; lemmas erose at the summit 7. FLUMINEA. 26b. Callus not bearded (lemmas cobwebby at base in Poa) ; lemmas not erose (slightly in Puccinellia) 27 27a. Lemmas keeled on the back (somewhat rounded in Poa scabrella and its allies) 28 28a. Spikelets strongly compressed, crowded in one-sided clusters at the ends of the stiff, naked panicle branches 21. DACTYLIS. 28b. Spikelets not strongly compressed, not crowded in one-sided clusters 29 29a. Lemmas awned from a minutely bifid apex (awnless or nearly so in Bromus unioloides and B. brizaeformis) ; spikelets large 2. BROMUS. 20b. Lemmas awnless ; spikelets small 8. POA. ' 27b. Lemmas rounded on the back (slightly keeled toward the summit in Festuca and Bromus) 30 30a. Glumes papery ; lemmas firm, strongly nerved, scarious-mar- gined ; upper florets sterile, often reduced to a club-shaped rudiment infolded by the broad upper lemmas; spikelets tawny or purplish, usually not green 24. MELICA. 30b. Glumes not papery ; upper florets not unlike the others 31 31a. Nerves of the lemma parallel, not converging at the sum- mit or but slightly so ; lemmas awnless mostly obtuse. 32 32a. Nerves prominent ; plants usually rather tall, grow- ing in woods or fresh-water marshes 4. PANICULARIA. 32b. Nerves faint ; plants low, growing in saline soil. 6. PUCCINELLIA. 31b. Nerves of the lemma converging at the smmmit ; lemmas awned or pointed (upper florets only minutely awn- tipped in Bromus brizaeformis) 33 33a. Lemmas entire, awned from the tip or pointed (minutely toothed in Festuca elmeri and F. gigantea} 3. FESTUCA. 33b. Lemmas awned or awn-tipped from a minutely bifid apex 2. BROMTJS. TRIBE 3, HORDEAE. Spikelets 1 to several flowered, sessile on opposite sides of a jointed or continuous axis forming symmetrical (not one-sided) spikes. This small but important tribe, found in the temperate regions of both hemispheres, includes our most important cereals, wheat, barley, and rye. The rachis is flattened or concave next to the spikelets, or in some genera is thickened and hollowed out, the spikelets being more or less inclosed in the hollows. In Triticum and its allies there is one spikelet at each node of the rachis; in Hordeum and its allies there are two or three at each node. In Lolium and its allies the spikelets are placed edgewise to the rachis, and the first or inner glume is suppressed except in the terminal spikelet. The rachilla of the spikelet disarticulates at maturity in several genera. In some species of Elymus and especially in Sitanion the glumes are very 12- BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. slender, extending into long awns, in the latter genus sometimes divided into several slender bristles. In this tribe the blades of the leaves bear on each side at the base a small appendage or auricle. Key to the genera of Hordeae. la. Spikelets solitary at each node of the rachis (rarely 2 in species of Agropyron, but never throughout) 2 2a. Spikelets 1-flowered, sunken in hollows in the rachis; spikes slender, cylindric; low annuals 3 3a. Lemmas awned ; florets lateral to the rachis 36. SCRIBNKRIA. 3b. Lemmas awnless ; florets dorsiventral to the rachis 4 4a. First glume wanting 42. LEPTUBTJS. 4b. First glume present, the pair standing in front of the spikelet 43. PIIOLIURUS. 2b. Spikelets 2 to several flowered, not sunken in the rachis 5 5a. Spikelets placed edgewise to the rachis ; first glume wanting except in the terminal spikelet 41. LOT.ITJM. " 5b. Spikelets placed flatwise to the rachis G 6a. Plants perennial i 33. AGROPYRON. 6b. Plants annual 7 7a. Glumes ovate, 3-nerved 34. TRTTICUM. 7b. Glumes subulate, 1-nerved 3.1. SKCAI.K. v Ib. Spikelets more than 1 at each node of the rachis 8 8a. Spikelets 3 at each node of the rachis, 1-flowered, the lateral pair pediceled, usually reduced to awns 40. HORDEUM. * 8b. Spikelets 2 at each node of the rachis, alike, 2 to 6 flowered 9 9a. Glumes wanting or reduced to 2 short bristles ; spikelets hor- izontally spreading at maturity ; spikes very loose 39. HYSTRIX. 9b. Glumes usually equaling the florets; spikelets appressed or ascending 10 lOa. Rachis continuous (rarely tardily disarticulating) ; glumes broad or narrow, entire 37. ELYMTJS. lOb. Rachis disarticulating at maturity; glumos subulate, extending into long awns, these and the awns of the lemmas making the spike very bristly 38. STTAXIOX. * Tin in: 4, AVKXKAE. Spikelets 2 to several flowered in open or contracted panicles, or rarely in racemes (solitary in Danthonia unispicata) ; glumes usually as long as or longer than the first lemma, commonly longer than all the florets; lemmas usually awned from the back or from between the teeth of a bifid apex, the awn bent, often twisted, the callus and rachilla joints usually villous. A rather small tribe widely distributed in both warm and cool regions. In our genera the rachilla is prolonged beyond the upper floret as a slender stipe (except in Aspris). The lemma is awnless or nearly so in Sphenopholis and in our species of Koeleria. These genera are placed in this tribe because they appear to be closely allied to Trisetum with which they agree in having oblanceolate glumes about as long as the first floret. GENERA OF GRASSES OF THE UNITED STATES. 13 Key to the genera of Avcncae. la. Spikelets awnless or the upper lemma mucronate (rarely short-awned in Splienopliolis) 2 2a. Articulation bolow the glumes ; glumes distinctly different in shape, the second widened above 4G. SIMIKMOPIIOLIS. 2b. Articulation above the glumes; glumes similar in shape, 44. KOKLKKIA. Ib. Spikelets awned (awnless in Trisetum wolfii) 3 3u. Florets 2, one perfect, the other staminate 4 4a. Lower floret staminate, the awn twisted, geniculate, ex- sorted 48. ARRHENATHERUM. 4b. Lower floret perfect, awnless; awn of upper floret hooked. 51. NOTHOLCUS. 3b. Florets 2 or more, all alike except the reduced upper ones 5 5a. Awn arising from between the teeth of a bifid apex, flat- tened, twisted ; inflorescence a simple panicle or reduced to a raceme or even to a single spikelet 52. DANTHONIA. 5b. Awn dorsal, not flattened ; lemma often bifid at apex G 6a. Spikelets large, the glumes over 1 cm. long 47. AVENA.*-*' 6b. Spikelets less than 1 cm. long 7 7a. Lemmas keeled, bidentate; awn arising from above the middle 45. TRISETUM. 7b. Lemmas convex ; awn from below the middle 8 8a. Rachilla prolonged behind the upper floret; lem- mas truncate and erose-dentate at summit 49. AIRA. 8b. Rachilla not prolonged ; lemmas tapering into 2 slender teeth 50. ASPRIS. , TRIBE 5, AGROSTIDEAE. Spikelets 1-flowered, usually perfect, arranged in open, contracted, or spikelike panicles, but not in true spikes nor in one-sided racemes. A large and important tribe, inhabiting more especially the tem- perate and cool regions. The articulation of the rachilla is usualty above the glumes, the mature floret falling from the persistent glumes, but in a few genera the articulation is below the glumes, the mature spikelet falling entire (Alopecurus, Cinna, Polypogon, Lycurus, and Limnodea). The palea is small or wanting in some species of Agrostis. In a few genera the rachilla is prolonged behind the palea as a minute bristle, or sometimes as a more pro- nounced villous stipe (Brachyelytrum, Limnodea, Cinna, three species of Agrostis, Gastridium, Calamagrostis, Ammophila, and Lagurus). In some genera the rachilla joint between the glumes and the lemma is slightly elongated, forming a hard stipe which remains attached to the mature fruit as a pointed callus. The callus is well marked in Stipa (especially in S. spartea and its allies) and in Aristida, the mature lemma being terete, indurate, and convolute, the palea wholly inclosed. In many genera the lemma is awned either from the tip or from the back, the awn being trifid in Aristida. 14 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. Key to the genera of Agrostideae. la. Glumes wanting; a low annual 58. COLEANTHTTS. Ib. Glumes present (the first obsolete in ^fuJllcnJ)crgia scJircbcri and sometimes in Brachyelytrum and Phippsia) 2 2a. Rachilla articulate below the glumes, these falling with the spikelet 3 3a. Spikelets in pairs in a spikelike panicle, one perfect, the other staminate or neuter, the pair falling together- 63. LYCUBUS. 3b. Spikelets all alike 4 4a. Glumes long-awned_: 62. POLYPOGON. 4b. Glumes awnless 5 5a. Rachilla not prolonged behind the palea ; panicle dense and spikelike ; glumes united toward the base, ciliate on the keel 61. ALOPECURUS. 5b. Rachilla prolonged behind the palea ; panicle nar- row or open, not dense; glumes not united, not ciliate on the keel , 6 6a. Panicle narrow; lemma with a slender bent twisted awn from the bifid apex 60. LIMNODEA. 6b. Panicle open and drooping ; lemma with a minute straight awn just below the entire apex 59. CINNA. 2b. Rachilla articulate above the glumes 7 7a. Fruit dorsally compressed, indurate, smooth and shining, awnless 74. MILIUM. 7b. Fruit laterally compressed or terete, awned or awnless 8 8a. Fruit indurate, terete, awned, the nerves obscure ; callus well developed, oblique, bearded 9 9a. Awn trifid, the lateral divisions sometimes short, rarely obsolete (when obsolete no line of demar- cation between awn and lemma as in the next) 77. ABISTIDA. 9b. Awn simple, a line of demarcation between the awn and the lemma 10 lOa. Awn persistent, twisted and bent, several to many times longer than the slender fruit ; callus sharp-pointed 76. STIPA. lOb. Awn deciduous, not twisted, sometimes bent, rarely more than 3 or 4 times as long as the plump fruit ; callus short, usually obtuse- 75. ORYZOPSIS. 8b. Fruit thin or firm, but scarcely indurate, if firm, the nerves prominent or evident ; callus not well devel- oped 11 lla. Glumes longer than the lemma (lemma equaling the glumes in Agrostis spica-venti, A. aequivalvis, and A. thurberiana) 12 12a. Panicle feathery, capitate, nearly as broad as long; spikelets woolly 66. LAGURUS. 12b. Panicle not feathery; spikelets not woolly 13 13a. Glumes compressed-carinate, abruptly mu- cronate, stiffly ciliate on the keels; panicle dense, cylindric or ellipsoid- 64. PHLEUM. 13b. Glumes not compressed-carinate, not ciliate 14 GENERA OF GRASSES OF THE UNITED STATES. 15 Key to the genera of Agrostideae Continued. 14a. Glumes saccate at base ; lemma long-awned ; inflorescence contracted, shining 65. GASTEIDIUM. 14b. Glumes not saccate at base ; lemma awned or awnless ; panicles open or contracted ] 15 15a. Florets bearing a tuft of hairs at the base from the short callus, the hairs at least half as long as the lemma; palea present 53. CALAMAGBOSTIS. 15b. Florets without hairs at the base or with short hairs rarely as much as half the length of the lemma (Agrostis hallii) ; palea usually small or wanting 56. AGROSTIS. " lib. Glumes not longer than the lemma, usually shorter (the awn tips longer in Muhlenbergia racemosa) 16 16a. Lemma awned from the tip or mucronate, 3 to 5 nerved (lateral nerves obsolete in Muhleribergia rcpcns) 17 17a. Rachilla prolonged behind the palea; floret stipitate. 73. BBACHYELYTETJM. 17b. Rachilla not prolonged ; floret not stipitate 68. MUHLENBERGIA. 16b. Lemma awnless or awned from the back 'i, 18 18a. Florets bearing a tuft of hairs at the base from the short callus; lemma and palea chartaceous, awnless 19 19a. Panicles spikelike; rachilla prolonged 54. AMMOPHILA. 19b. Panicles open ; rachilla not prolonged 55. CALAMOVILFA. 18b. Florets without hairs at base 20 20a. Nerves of lemma densely silky 70. BLEPHARONEURON. 20b. Nerves of lemma not silky 21 21a. Caryopsis at maturity falling from the lemma and palea; seed loose in the pericarp, this usually opening when ripe; lemma 1-nerved 22 22a. Inflorescence capitate in the axils of broad bracts 71. CRYPSIS. 22b. Inflorescence an open or contracted panicle. 69. SPOROBOLUS. 21b. Caryopsis not falling from the lemma and palea, remaining permanently inclosed in them; seed adnate to the pericarp 23 23a. Panicles few-flowered, slender, rather loose; glumes minute, unequal, the first often want- ing; a low arctic alpine perennial 57. PHIPPSIA. 23b. Panicle many-flowered, spikelike ; glumes well developed, about equal 24 24a. Panicle short, partly inclosed in the sheath ; low annual 72. HELEOCHLOA. 24b. Panicle elongate; perennial 67. EPICAMPES. TRIBE 6, NAZIEAE. Spikelets subsessile in short spikes of 2 to 5 (single in Oster- damia), each spike falling entire from the continuous axis, usually 1-flowered, all perfect, or perfect and staminate together in the same spike; glumes usually firmer than the lemma and palea, sometimes awned, the lemma awnless. This small and unimportant tribe is known also as Zoysieae. In Osterdamia the spikelets are single and have only one glume, this 16 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. coriaceous, much firmer than the lemma and palea, the palea some- times obsolete. Key to the yenera of Nazieae. la. Spikelets single ; first glume wanting 79. OSTERDAMIA. Ib. Spikelets in clusters of 2 to 5 ; first glume present 2 2a. Spikelets bearing hooked spines on the second glume, the group forming a little bur 78. NAZIA. 2b. Spikelets not bearing hooked spines, mostly cleft and awned 3 3a. Groups of spikelets erect, the spike not one-sided 80. HILABIA. 3b. Groups of spikelets nodding along one side of the delicate axis 81. AEGOPOGON. TRIBE 7, CHLOKIDEAE. Spikelets 1 to several flowered, in 2 rows on one side of a con- tinous rachis forming one-sided spikes or spikelike racemes, these solitary, digitate, or racemose along the main axis. A large and rather important tribe, confined mostly to warm regions. The group is heterogeneous, the only common character of the genera (aside from the characters that place them in Poatae) being the arrangement of the spikelets in one-sided spikes. Chloris and the allied genera form a coherent group, in which the spikelet consists of one perfect floret and, above this, one or more modified or rudimentary florets. Leptochloa, Eleusine, and their allies, with several-flowered spikelets, are more nearly related to certain genera of Festuceae. The spike is reduced to two or three spikelets or even to one spikelet and is sometimes deciduous from the main axis in Cathestecum and in some species of Bouteloua. In Campulosus there are two sterile florets below the perfect one. Key to the genera of Chlorideae. la. Plants monoecious or dioecious ; a low stoloniferous perennial- 98. BTJLBIUS. Ib. Plants with perfect flowers 2 2a. Spikelets with more than one perfect floret 3 3a. Inflorescence a few-flowered head or capitate panicle hidden among the sharp-pointed leaves; a low spreading an- nual 97. MUNBOA. 3b. Inflorescence exserted 4 4a. Spikes solitary, the spikelets distant, appressed, sev- eral-flowered 83. TEIPOGON. 4b. Spikes more than 1 5 5a. Spikes numerous, slender, racemose on an elongate axis 82. LEPTOCHLOA. 5b. Spikes few, digitate or nearly so 6 6a. Rachis of spike extending beyond the spike- lets 85. DACTYLOCTENITJM. 6b. Rachis not prolonged 84. ELEUSINE. 2b. Spikelets with only 1 perfect floret, often with additional imper- fect florets above__ 7 GENEKA OF GRASSES OF THE UNITED STATES. 17 Key to the genera of Chlorideac Continued. 7a. Spikelets without additional modified florets, the rachilla sometimes prolonged 8 Sa. Rachilla articulate below the glumes, the spikelets falling entire- 9 9a. Glumes unequal, narrow 90. SPAETINA. 9b. Glumes equal, broad and boat shaped 89. BECKMANNIA. 8b. Rachilla articulate above the glumes 10 lOa. Spikes digitate; rachilla prolonged 86. CAPRIOLA. lOb. Spikes racemose along the main axis ; rachilla not prolonged. 11 Ha. Spikes slender, divaricate, the main axis elongating and becoming loosely spiral in fruit 88. SCHEDONNARDUS. lib. Spikes short and rather stout, appressed, the axis un- changed in fruit 87. WUXKOMMIA. 7b. Spikelets with 1 or more modified florets above the perfect one_ 12 12a. Spikelets with 2 sterile florets below the perfect one; second glume bearing a squarrose spine on the back; spike single, recurved 91. CAMPULOSUS. 12b. Spikelets with no sterile florets below the perfect one; second glume without a squarrose spine ; spikes usually several 13 13a. Spikes digitate or nearly so 14 14a. Fertile lemma 1-awned or awnless 93. CHLOBIS. 14b. Fertile lemma 3-awned 94. TKICHLOEIS. 13b. Spikes racemose along the main axis 15 15a. Spikelets distant, appressed ; spikes slender, elongate. 92. GYMNOPOGON. 15b. Spikelets contiguous or crowded, not appressed ; spikes usually short and rather stout -. 16 16a. Spikelets 3 in each spike, the 2 lateral staminate or rudimentary ; spikes falling entire 96. CATHESTECUM. 16b. Spikelets 2 to many (rarely 1) in each spike, all alike ; spikes usually persistent, the florets falling. 95. BOUTELOUA. TRIBE 8, PHALARIDEAE. Spikelets with one perfect terminal floret and, below this, a pair of staminate or neuter florets. A small tribe of about six genera, only three of which are found in the United States. In Phalaris the lateral florets are reduced to minute scalelike lemmas closely appressed to the edges of the fertile floret. In Torresia the lateral florets are staminate and as large as the fertile floret. Key to the genera of Phalarideae. la. Lateral florets staminate ; spikelets brown and shining 99. TORRESIA. Ib. Lateral florets neuter ; spikelets green or yellowish 2 2a. Lateral florets reduced to small awnless scalelike lemmas ; spike- lets much compressed laterally - 101. PHALARIS. 2b. Lateral florets consisting of awned hairy sterile lemmas exceed- ing the fertile floret ; spikelet terete 100. ANTHOXANTHTJM, 97769 19 Bull. 772 2 18 BULLETIN 112, U. S. DEPARTMENT OF AGRICULTURE. TRIBE 9, ORYZEAE. Spikelets 1-flowered, perfect, strongly laterally compressed, panic- ulate ; glumes reduced or wanting ; palea apparently 1-nerved ; stam- ens 6. A small tribe whose affinities are not evident. It includes rice, the important food plant. - Key to the genera of Oryzeae. Glumes minute; lemma often awned 102. ORYZA. Glumes wanting; lemma awnless 103. HOMALOCENCHRUS. TRIBE 10, ZIZANIEAE. Spikelets unisexual, the pistillate terete or nearly so; glumes shorter than the lemma, usually one or both obsolete, the pedicel dis- articulating below the spikelet. A small tribe of uncertain affinities; the species aquatic or sub- aquatic, of no economic importance except the Indian rice (Zizania). Key to the genera of Zizanieae. la. Culms slender ; plants low ; staminate and pistillate spikelets borne in separate inflorescences 2 2a. Inflorescence a few-flowered spike ; plants not stoloniferous. 107. HYDROCHLOA. 2b. Inflorescence a panicle; plants stoloniferous 106. LUZIOLA. Ib. Culms robust ; plants tall ; staminate and pistillate spikelets borne in the same panicle - 3 3a. Plants annual; pistillate spikelets on the ascending upper branches, the staminate on the spreading lower branches of the panicle '. 105. ZIZANIA. 3b. Plants perennial; pistillate spikelets at the ends, the staminate below on the same branches of the panicle 104. ZIZANIOPSIS. TRIBE 11, MELINIDEAE. Spikelets disarticulating below the glumes, these very unequal, the first minute, the second and the sterile lemma equal, membranaceous, strongly nerved, the latter bearing a slender awn from the notched summit ; fertile lemma and palea thinner in texture, awnless. A tribe of about a dozen genera, none of w r hich is represented in the United States. The only economic species is Melinis minutiftora (seep. 212). TRIBE 12, PANICEAE. Spikelets with one perfect terminal floret and below this a sterile floret and two glumes; fertile lemma and palea indurate or at least firmer than the glumes and sterile lemma; articulation below the spikelet. A large tribe, confined mostly to warm regions, and containing few economic species. The first glume is wanting in some genera, such as Paspalum, and rarely the second glume also (Eeimarochloa). GENERA OF GRASSES OF THE UNITED STATES. 19 The spikelets are usually awnless, but the glumes and sterile lemma are awned in Echinochloa and Oplismenus, and the second glume and sterile lemma in Tricholaena. In Eriochloa and in some species of Brachiaria the fertile lemma is awn-tipped. In Chaetochloa there are, beneath the spikelet, one or more bristles, these representing sterile branchlets. In Pennisetum similar bristles form an involucral cluster, falling with the spikelet. In Cenchrus the bristles are united, forming a bur. The spikelets are of two kinds in Amphi- carpon, aerial and subterranean. The culms are woody and perennial in Lasiacis and Olyra. Key to the genera of Paniceae. la. Spikelets of two kinds 2 2a. Spikelets all perfect, but those of the aerial panicle not perfect- ing grains; the fruitful spikelets borne on subterranean branches 127. AMPHICARPON. 2b. Spikelets unisexual, the pistillate above, the staminate below on the branches of the same panicle ; blades broad, elliptic. OLYRA. (See p. 252.) Ib. Spikelets all of one kind 3 3a. Spikelets sunken in the cavities of the flattened corky rachis. 112. STENOTAPHEUM. 3b. Spikelets not sunken in the rachis 4 4a. Spikelets subtended or surrounded by 1 to many distinct or more or less connate bristles, forming an involucre 5 5a. Bristles persistent, the spikelets deciduous- 124. CHAETOCHLOA. 5b. Bristles falling with the spikelets at maturity G 6a. Bristles not united at base, slender, often plumose. 125. PENNISETUM. 6b. Bristles united into a burlike involucre, the bristles retrorsely barbed 126. CENCHRUS. 4b. Spikelets not subtended by bristles 7 7a. Glumes or sterile lemma awned (awn short and con- cealed in the silky hairs of the spikelet in Tricholaena, awn reduced to a point in Echinochloa colonuni) 8 8a. Inflorescence paniculate ; spikelets silky_ 123. TRICHOLAENA. 8b. Inflorescence of unilateral simple or somewhat com- pound racemes along a common axis; spikelets smooth or hispid, not silky 9 9a. Blades lanceolate, broad and thin ; glumes 2- lobed, awned from between the lobes. 121. OPLISMENUS. 9b. Blades long and narrow ; glumes awned from the tip 122. ECHINOCHLOA. 7b. Glumes and sterile lemma awnless 10 lOa. Fruit cartilaginous-indurate, flexible, usually dark colored, the lemma with more or less prominent white hyaline margins, these not inrolled 11 Ha. Spikelets covered with long silky hairs, ar- ranged in racemes, these panicled 109. VALOTA. lib. Spikelets glabrous or variously pubescent but not long-silky 12 20 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. Key to the genera of Paniceae* Continued. 12a. Spikelets in slender racemes more or less digitate at the summit of the culms 110. SYNTHEBISMA. 12b. Spikelets in panicles 13 13a. Fruiting lemma boat shaped; panicles narrow. 108. ANTHAENANTIA. 13b. Fruiting lemmas convex; panicles diffuse 111. LEPTOLOMA. lOb. Fruit chartaceous-indurate, rigid 14 14a. Spikelets placed with the back of the fruit turned away from the rachis of the racemes, usually single (not in pairs) 15 15a. First glume and the rachilla joint forming a swollen ring- like callus below the spikelet 113. ERIOCHLOA. 15b. First glume present or wanting, not forming a ringlike callus below the spikelet 16 16a. First glume present ; racemes racemose along the main axis , 114. BRACHIARIA. 16b. First glume wanting ; racemes digitate or subdigitate. 115. AXONOPUS. 14b. Spikelets placed with the back of the fruit turned toward the rachis of the spikelike racemes, or pedicellate in panicles 17 17a. Fruit long-acuminate; both glumes wanting- 116. REIMAROCHLOA. 17b. Fruit not long-acuminate, at least one glume present 18 ISa. First glume typically wanting; spikelets plano-convex, subsessile in spikelike racemes 117. PASPALUM. ISb. First glume present ; spikelets usually in panicles 19 19a. Second glume inflated-saccate, this and the sterile lemma much exceeding the stipitate fruit. 120. SACCIOLEPIS. 19b. Second glume not inflated-saccate 20 20a. Culms woody and bamboolike; fruit with a tuft of down at the apex 119. LASIACIS. 20b. Culms herbaceous ; no tuft of down at the apex of the fruit 118. PANICUM. TRIBE 13, ANDROPOGONEAE. Spikelets in pairs along a rachis, the usual arrangement being one of the pair sessile and fertile, the other pedicellate and staminate or neuter, or rarely wanting, only the pedicel present ; fertile spike- let consisting of one perfect terminal floret and, below this, a stami- nate or neuter floret, the lemmas thin or hyaline, and two awnless glumes, one or usually both firm or indurate. A large tribe, confined mostly to warm regions. The rachis is usually jointed, disarticulating at maturity, with the spikelets at- tached. In a few genera it is thickened. Sometimes the racemes are shortened to 1 or 2 joints and borne on branches, the whole forming a panicle (as in Holcus and Sorghastrum) instead of a series of racemes. In a few genera the spikelets of the pair are alike. In Traclwpogon the fertile spikelet is pedicellate and the sterile one nearly sessile. GENERA OF GRASSES OF THE UNITED STATES. 21 Key to the genera of Andropogoneae. la. Spikelets all perfect, surrounded by a copious tuft of soft hairs 2 2a. llacliis continuous, the spikelets falling ; spikelets of the pair un- equally pedicellate 3 3a. Racemes in a narrow spikelike panicle, spikelets awn- less > 128. IMPERATA. 3b. Racemes in a broad fan-shaped panicle; spikelets awned. 129. MlSCANTHtJS. 2b. Rachis breaking up into joints at maturity with the spikelets at- tached ; one spikelet sessile, the other pedicellate 4 4a. Spikelets awnless 130. SACCHARUM. 4b. Spikelets awned 131. ERIANTHTJS. Ib. Spikelets unlike, the sessile perfect, the pedicellate sterile (sessile spikelet staminate, pedicellate spikelet perfect in Trachypogon) 5 5a. Pedicel thickened, appressed to the thickened rachis joint (at least parallel to it) or adnate to it; spikelets awnless, ap- pressed to the joint G 6a. Rachis joint and pedicel adnate, forming a short flat joint, this sunken in the open side of the globose first glume of the sessile spikelet; sterile spikelet conspicuous 140. RYTILIX. 6b. Rachis joint and pedicel distinct, the sessile spikelet ap- pressed to them, its first glume lanceolate 7 7a. Racemes subcylindric ; rachis joints and pedicels glabrous, much thicker at the summit, the spikelets sunken in the hollow below ; sterile spikelet rudimentary 130. MANISURIS. 7b. Racemes flat ; rachis joints and pedicels woolly, not much thicker at the summit; sterile spikelet staminate or neu- ter 138. ELYONURUS. 5b. Pedicel not thickened (if slightly so the spikelets awned), neither appressed nor adnate to the rachis joint, this usually slender ; spikelets usually awned ^ 8 8a. Fertile spikelet with a hairy-pointed callus, formed of the attached supporting rachis joint or pedicel ; awns strong 9 9a. Racemes reduced to a single joint, long-peduncled in a simple open panicle 135. RHAPHIS. 9b. Racemes of several to many joints, single 10 lOa. Primary spikelet subsessile, sterile, persistent on the continuous axis after the fall of the fertile pedi- cellate spikelet, the pedicel forming the callus. 137. TRACHYPOGON. lOb. Primary spikelet sessile, fertile; pedicellate spike- let sterile ; lower few to several pairs of spikelets all staminate or neuter 136. HETEROPOGON. 8b. Fertile spikelet without a callus, the rachis disarticulating immediately below the spikelet ; awns slender 11 lla. Racemes of several to many joints, solitary, digitate, or aggregate 132. ANDROPOGON. lib. Racemes reduced to one or few joints, these mostly peduncled in a subsimple or compound panicle 12 12a. Pedicellate spikelets staminate 133. HOLCUS. 12b. Pedicellate spikelets wanting, the pedicel only present 134. SORGHASTRUM. BULLETIN 772, XT. S. DEPARTMENT OF AGRICULTURE. TRIBE 14, TEIPSACEAE. celets unisexual, the staminate in pairs, or sometimes in threes 2-flowered, the pistillate usually single, 2-flowered, the lower floret sterile, imbedded in hollows of the thickened articulate axis and fall- ing attached to the joints, or inclosed in a thickened involucre or sheath or, in Zea, crowded in rows on a thickened axis (cob) ; glumes membranaceous or thick and rigid, awnless; lemmas and palea hyaline, awnless. Plants monoecious. This small tribe of seven genera is scarcely more than a subtribe of Andropogoneae. It is also known as Maydeae. Key to the genera of Tripsaceae. la. Staminate and pistillate spikelets in separate inflorescences, the first in a terminal tassel, the second in the axils of the leaves 2 2a. Pistillate spikes distinct, the spikelets embedded . in the hardened rachis, this disarticulating at maturity 142. ETJCHLAENA. 2b. Pistillate spikes grown together forming an ear. the grains at maturity much exceeding the glumes 143. ZEA. Ib. S-taminate and pistillate spikelets in separate portions of the same spike, the pistillate below 3 3a. Spikes short, the 1 or 2 flowered pistillate portion inclosed in a beadlike sheathing bract 144. Coix. 3b. Spikes many-flowered, the pistillate portion breaking up into several 1-seeded joints; no beadlike sheathing bract 141. TEIPSACUM. DESCRIPTIONS OF THE GENERA. 1. BAMBOSEAE, THE BAMBOO TRIBE. 1. ARTJNDINARIA Michx. Spikelets few to many flowered, large, compressed, the rachilla disarticulating above the glumes and between the florets ; glumes un- .equal, shorter than the lemmas, the first sometimes wanting ; lemmas acute or acuminate or mucroiiate, faintly many-nerved; palea about as long as the lemma, prominently 2-keeled. Shrubs or tall reeds, with woody perennial branching culms, flat blades with petioles articulate with the sheaths, and loose racemes or panicles. Species about 25, in the Tropics of both hemispheres; 2 species in the southeastern United States. Type species: Arnndinarin macrosperma Michx. Arundinaria Michx., Fl. Bor. Amer. 1 : 73. 1803. One species described. Miegin Pers., Syn. PI. 1:101. 1805. A single species, based on Arundinaria macrosperma Michx., is included. Macronax Raf., Med. Repos. ser. 2. 5: 353. 1808. Based on "The Arundi- naria of Michaux." Our two species, Anmdinaria tecta (Walt.) Muhl. (fig. 1) and A. macrosperma (PL I), are the only native representatives of the tropi- cal tribe Bamboseae, or Bambuseae, the bamboos. Our species are known, respectively, as small and large cane. Both flower infre- Bui. 772, U. S. Dept. of Agriculture. PLATE LARGE CANE (ARUNDINARIA MACROSPERMA). INFLORESCENCE, LEAVES, FLORETS, AND RIPE GRAINS. Bui. 772, U. S. Dept. of Agriculture. PLATE II, MEADOW FESCUE (FESTUCA ELATIOR) IN FLOWER. GENERA OF GRASSES OF THE UNITED STATES. 23 FIG. 1. Small cane, Arundinaria tccta. Flowering shoot and leafy branch, X a ; spike- let and floret, X 2. 24 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. quently. The first is rarely over G feet tall, with drooping blades^ the inflorescence on leafless or nearly leafless shoots from the base of the plant. This is found from Maryland southward. The other species grows to a height of as much as 25 or 30 feet and forms, in the alluvial river bottoms of the Southern States, dense thickets called canebrakes. The racemes are borne on leafy branches, the species flowering less frequently than the small cane. Stock are fond of the young plants and of the leaves and seeds, and both species furnish much forage in localities where they are abun- dant. The young shoots are sometimes used as a potherb. The stems or culms of the large cane are used for fishing rods, pipestems, baskets, mats, light scaffolding, and for a variety of other purposes. 2. FESTUCEAE, THE FESCUE TRIBE. 2. BROMTJS L., the brume-grasses. . Spikelets several to many flowered, the rachilla disarticulating above the glumes and between the florets ; glumes unequal, acute, the first 1 to 3 nerved, the second usually 3 to 5 nerved ; lemmas convex on the back or keeled, 5 to 9 nerved, 2-toothed at the apex, awnless or usually awned from between the teeth; palea usually shorter than the lemma. Annual or perennial, low or rather tall grasses, with closed sheaths, flat blades, and open or contracted panicles of large spikelets. Species about 100, in temperate regions; about 43 species in the United States, of which -IT are introductions, mostly from Europe. Type species: Bromus sccalinus L. Bronras L., Sp. PI. 76, 1753 ; Gen. PI., eel. 5, 33. 1754. Linnaeus describes 11 species, all but the last 2 of which are still retained in the genus. The cita- tion given after Brornus in the Genera I'lantarum is "Mont. 32." This" refers to figure 32 in the plate accompanying Monti's Catalog! Stirpium Agri Bononiensis Prodromus, published in 1719. This figure represents a spikelet of Bromus secalinus, or of a closely allied species. As Brotnu* sct-uH-mis is the first species described in the Species Plantarum and was described in the flora of Sweden, this species is chosen as the type. Ceratochloa Beauv., Ess. Agrost. 75, pi. 15, f. 7. 1812. A single species in- cluded. Festuca unioloides Willd., which is the basis of Bromus it mol aides (Willd.) H. B. K. Zerna Panz., Denkschr. Baier. Akad. Wiss. Miiench. 4: 296. 1813. (Ideen Gatt. Graser 46, pi. 11, f. 3.) Eleven species are included. Bromus stcrilis L., the one figured, is taken as the type. Serrafalcus Part., Rar. PI. Sic. 2: 14. 1840. Six species are included. Bro- mus rac-cmosus L., on which the first species is based, is taken as the type. Forasaccus Bubani, Fl. Pyren. 4 : 380. 1901. Proposed for Bromus L., not Bromus of the ancients, which is said to be wild oats. The section Ceratochloa has large compressed spikelets with com- pressed-keeled glumes and lemmas. One species, Bromus unioloides (Willd.) H. B. K., is cultivated as a forage grass under the name of rescue grass or Schrader's brome-grass. This is an annual or bi- ennial grass 1 to 2 feet tall, with pubescent sheaths and narrow pani- cles of smooth spikelets as much as an inch long, the lemmas acumi- GENERA OF GRASSES OF THE UNITED STATES. 25 nate or awn-tipped. Rescue grass is a native of South America and is cultivated occasionally in our Southern States for winter forage. The other species of this section are natives of the western half of the United States. They are all perennials and have large awned spikelets. Bromus carinatus Hook, and Am. and B. marginatus Nees are common on the Pacific coast. They have pubescent or scabrous spikelets, the first with an awn longer than the lemma, the second with an awn shorter than the lemma. Bromus carinatus often appears like an annual, flowering the first year. The species of Bromus in which the spikelets are not compressed- keeled fall into two rather well-marked groups, perennials and an- nuals. The most important species of the first group is Bromus inermis Leyss., a European species known also as awnless brome- grass, Hungarian brome-grass, smooth brome-grass, and brome-grass. It is erect, 2 to 3 feet tall, with creeping rhizomes and narrow, many- flowered panicles with erect or ascending branches and smooth nar- row spikelets about an inch long, the lemmas acute, awnless, or nearly so. Awnless brome-grass is cultivated for hay and pasture in the northern portion of the Great Plains from northern Kansas to Minnesota and Montana. It is more drought resistant than timothy and in the region mentioned can be grown farther west than that species, but does not thrive south of central Kansas. All the other perennial species are natives except B. erectus, occasionally intro- duced from Europe, and all have distinctly awned lemmas. Bromus purgans L. is a common woodland species in the Eastern States. This has an open drooping panicle with nearly terete spikelets, the lemmas pubescent over the back. The closely allied and equally com- mon B. ciliatus L. (fig. 2) differs in having lemmas glabrous on the back and pubescent on the margins only. Several species are found in the Western States, B. porteri (Coult.) Nash, with close drooping panicle and softly pubescent spikelets, being common in the Rocky Mountains. The group of annuals includes weedy species introduced mostly from Europe. The best known of these in the Eastern States is Bromus seealinus (fig. 3), chess or cheat, a weed of waste places and sometimes infesting grain fields. Formerly it was believed by the credulous that under certain conditions wheat changed into chess. Chess in a wheat field is due to chess seed in the soil or to chess seed in the wheat sown. Chess is a smooth grass 1 to 3 feet tall, with flat blades and open duooping panicles of smooth turgid spikelets, the lemmas broad and inrolled above, the awn about as long as the lemma. Bromus commutatus Schrad. differs in having pubescent sheaths. On the Pacific coast the annual species of Bromus have become conspicuous. They thrive on all open ground at lower altitudes in 26 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. FIG. 2. Wild brome-grass, Bromus ciliatus. Plant, X i ; spikelet and floret, X 5. GENEKA OF GRASSES OF THE UNITED STATES. 27 FIG. 3. Chess (cheat), Bromus secalinus. Plant, X 2 ; spikelet and floret, X 5. 28 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. spring and early summer, and on the approach of the summer dry season they ripen their seed and turn brown. They often cover vast areas and have become a great pest. The commonest species are B. rub&ns L., with contracted panicles of narrow usually purplish spikelets; B. hordeaceus L., with compact panicles of short turgid usually pubescent spikelets like those of B. secodmus; B. villosus Forsk., with open rather few-flowered panicles and narrow spike- lets with awns as much as 2 inches long; and B. tectorum L. (fig. 4), a rather small softly pubescent species, with drooping panicles of narrow spikelets. Bromws trimi Desv., found chiefty in the desert regions of California, introduced from Chile, is peculiar in having a bent awn twisted below. Bromus arenarius Labill., a recent intro- duction from Australia, is becoming common. This has an open panicle with capillary curved pedicels and short, pubescent spikelets. The perennial species of Bromus are important forage grasses on the mountain ranges of the Western States. The annual species are good forage grasses w T hen they are young, but they are rather eva- nescent. The fruits of B. villosus. and B. rubens and their allies are injurious to stock, the sharp-pointed florets working their way into the eyes and nostrils. BromMs secalmm is grown for hay in Wash- ington, in Oregon, and in Georgia. For a revision of the species of Bromus found in the United States, see Shear, U. S. Dept. Agr., Div. Agrost. Bull. 23. 1900. 3. FESTUCA L., the fescue grasses. Spikelets few to several flowered, the rachilla disarticulating above the glumes and between the florets; glumes narrow, acute, unequal, the first sometimes very small; lemmas rounded on the back, mem- branaceous or somewhat indurate, 5-nerved, the nerves often obscure, acute or rarely obtuse, awned from the tip or rarely from a minutely bifid apex. Annual or perennial low or rather tall grasses of varied habit, the spikelets in narrow or open panicles. Species about 100, in the tem- perate and cool regions; about 40 species in the United States, 7 of which are introductions from Europe. Type species: Festuca ovina L. P'estuca L., Sp. PI. 73, 1753; Gen. PI., ed. 5, 33. 1754. Linnaeus describes 11 species. Festuca ovina is chosen as the type, as it is the first of the original species that is economic and is described in the flora of Sweden. Most of the original species are still retained in Festuca but F. flecumbens is now placed in Sieglingia, F. fluitans in Panicularia, and F. cristata in Koeleria (.K. phleoides). Vulpia Gmel., Fl. Badens. 1: 8. 1805. One species, V. 'myuros, based on Festuca myuros L., is described, and two species of Festuca having a single stamen are mentioned in a note. Festuca myuros is taken as the type. Schedonorus Beauv., Ess. 'Agrost. 99, pi. 19, f. 2. 1812. The first of the 25 species included and the one figured is "Bromus elatior" (L.) KoeL, based on Festuca elatior. The figure shows a floret with a short awn below the minutely bidentate apex, as found in occasional specimens of F. elatior, which species is taken as the type. GENERA OF GRASSES OF THE UNITED STATES. 29 FIG. 4. Downy brome-grass, Bromm tectorum. Plant, X J ; splkelet and floret, X 5. 30 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. Dasiola Raf., Neogenyt. 4. 1825. " Type Festuca monandra " Ell., renamed D. elliottea Raf. This is F. scinrea Nutt. Chloaninia Raf., Neogenyt. 4. 1825. Two species are in- cluded, Festuca te- ncUtt and F. liromoi- dcs. The first, which is F. octo flora Walt., is taken as the type. Hesperochloa (Pi- per) Rydb., Bull. Torrey Club 39: 106. 1912. Based on Fes- tuca subgenus Hes- perochloa Piper, the type and only species of which is F. confi.n-ix Vasey. Wasatchia Jones, Contr. West. Bot. 14 : 16. 1912. A single species is included, ir. Jcinffii (Watson) Jones, based on Pova. Plant, X i ; spikelet and floret, X 5. 78 BULLETIN 772, JJ. S. DEPARTMENT OF AGRICULTURE. The three species are found in sandy soil in the Eastern States, Triplasis purpivrea (fig. 36) from Maine to Florida and from the Great Lakes to Texas. Triplasis intermedia is confined to Florida ; T. americana is found from North Carolina to Florida. All the spe- cies, besides the small panicles of cleistogamous spikelets in the upper sheaths, have additional cleistogamous spikelets, reduced to a single large floret, at the bases of the lower sheaths. The culms break at the nodes bearing these cleistogenes, the ripe seed remaining attached to the internode. The species are of no importance except as they tend to hold sandy soil. For a revision of the species of Triplasis, see Nash, Bull. Torrey Club 25:561-565. 1898. 28. BLEPHAKIDACHNE Hack. Spikelets 4-flowered, the rachilla disarticulating above the glumes but not between the florets; glumes nearly equal, about as long as the spikelet, compressed, 1-nerved, thin, acuminate, smooth; lemmas deeply 3-lobed, 3-nerved, the first and second sterile, containing a palea but no flower, the third fertile, the fourth reduced to a 3-awned rudiment. Low annuals or perennials, with short, congested, few-flowered panicles scarcely exserted from the subtending leaves. Species two ; one in Argentina, one in Nevada. Type species: Eremochloe kingii S. Wats. Eremochloe S. Wats., in King, Geol. Expl. 40th Par. 382, pi. 40, 1871, not Eremochloa Biise, 1854. Two species are described, one E. kingii from Nevada and the other, in a footnote, E. bigelovii, from southern New Mexico. The two specimens are to be referred to the same species. Blepharidachne Hack., in Engl. and Prantl, Pflanzenf am. 2 2 : 126. 1887. In a footnote the name Blepharidachne is substituted for Eremochloe S. Wats., because of the earlier Eremochloa Biise. The author of Blepharidachne is given as " Hook.," a typographical error for Hack. Blepharidachne Jcingii (S. Wats.) Hack. (fig. 37), found on the plains and foothills of Nevada (and New Mexico according to Watson), has been collected only a few times. A second species, Blepharidachne benthamiana (Hack.) Hitchc. (Munroa benthamiana Hack. 1 ) grows in dry regions of Argentina. In habit it resembles our Munroa squarrosa, but in floral structure it agrees with Blepharidachne, having two sterile florets, one fertile floret, and a 3-awned rudiment. 29. OECTJTTIA Vasey. Spikelets several-flowered, the upper florets reduced; rachilla per- sistent, continuous, the florets falling away or tardily disarticulating ; glumes nearly equal, shorter than the lemmas, broad, irregularly 2 to 5 1 In Kuntze, Rev. Gen. PI. 3 2 : 357. 1898. GENERA OF GRASSES OF THE UNITED STATES. 79 r< FIG. 36. Triplasis purpurea. Plant, X J ; spikelet, floret (above) showing beard on tbx nerves of the palea and cleistogene (at left), a cleistogamous fertile 1-flowered spikelet from the axil of a lower leaf, aJl X 5. 80 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. toothed, many-nerved, the nerves extending into the teeth; lemmas firm, prominently 13 to 15 nerved, the broad summit with 5 long FIG. 37. Blepharidachne kingii. Plant, X 1 ; spikelet and perfect floret, the latter showing the rudiment behind the palea, X 5. teeth or with numerous short teeth ; palea broad, 2-nerved, as long as the lemma. Low cespitose annuals, with short blades and terminal spikelike racemes, the spikelets rel- atively large, appressed, the upper aggregate, the lower more or less remote. Species two ; California and Lower California. Type species: Orcuttia call- f arnica Vasey. Orcuttia Vasey, Bull. Tor- rey Club 13 : 219, pi. 16. 1886. The one species described was collected by C. R. Orcutt at San Quentin Bay, Lower Cali- fornia. Our species, both in California, are Orcuttia greenei Vasey, from Chico, of which only the type collection is known, and 0. calif omica (fig. 38), has been collected no. 8 a-o ra , io cau/orntca. Plant, x i; .pikelet and floret, the latter without a joint of the at GrOOSe Valley, llielat- rachilla, this not disarticulating, X 5. ter S p ec i es i s distinguished by having 5-toothed lemmas; 0. greenei has truncate lemmas, the nerves extending into short points. GENERA OF GRASSES OF THE UNITED STATES. 81 30. SCLEROPOGON Philippi. Plants dioecious. Staminate spikelets several-flowered, pale, the rachilla not disarticulating; glumes about equal, a perceptible inter- node between, membranaceous, long-acuminate, 1-nerved or obscurely 3-nerved, nearly as long as the first lemma; lemmas similar to the glumes, somewhat distant on the rachilla, 3-nerved or obscurely 5- nerved, the apex mucronate; palea obtuse, shorter than the lemma. Pistillate spikelets several -flowered, the upper florets reduced to awns, the rachilla disarticulating above the glumes but not separat- ing between the florets or only tardily so; glumes acuminate, 3- nerved, with a few fine additional nerves, the first about half as long as the second ; lemmas narrow, 3-nerved, the nerves extending into 3 slender, scabrous, spreading awns, the florets falling together forming a cylindric many-awned fruit, the lowest floret with a sharp-bearded callus as in Aristida ; palea narrow, the two nerves near the margin, produced into short awns. A perennial stoloniferous grass, with short flexuous blades and narrow few-flowered racemes or simple panicles, the staminate and pistillate strikingly different in appearance. Species one; Chile to southwestern United States. Type species: Scleropogon brevifolius Philippi. Scleropogon Philippi, Anal. Univ. Chile 36: 205. 1870. Only one species de- scribed. Lesourdia Fourn., Bull. Soc. Bot. France 2 7 : 102, pi. 3, 4. 1880. Two species Are proposed, L. multlflora and L. kar wins ky ana, both referable to the same species, Scleropogon brevifolius. This species (fig. 39) is found on semiarid plains and open valley lands from southern Colorado to Texas and Arizona and southward. The mature pistillate spikelets break away and with their numer- ous long spreading awns form " tumbleweeds " that are blown before the wind. The pointed barbed callus readily penetrates clothing or wool, the combined florets acting like the single floret of the long- awned aristidas. As a forage grass, this is inferior to grama ; but on overstocked ranges, where it tends to become established, it is use- ful in preventing erosion. It is called burro grass. 31. COTTEA Kunth. Spikelets several-flowered, the uppermost reduced, the rachilla dis- articulating above the glumes and between the florets; glumes two, about equal, nearly equaling the lower lemma, with several parallel nerves ; lemmas rounded on the back, villous below, prominently 9 to 11 nerved, the nerves extending partly into awns of irregular size and partly into awned teeth ; palea awnless, a little longer than the body of the lemma. 97769 19 Bull. 772 6 82 BULLETIN 772, TJ. S. DEPARTMENT OF AGRICULTURE. FIG. 39. Burro grass, Scleropogon brevifolius. Pistillate (left) and staminate plants, X i ; pistillate spikelet, X 2 ; pistillate and staminate floret, X 5. GENERA OF GRASSES OF THE UNITED STATES. 83 An erect tufted branching perennial, with oblong open panicles. Species one; western Texas to southern Arizona and southward to Argentina. Type 4 species: Cottcu pappophoroides Kunth. Cottea Kunth, Rev. Gram. 1: 84. 1829. A single species mentioned, from Peru. This genus is allied to Pappophorum and very closely related to Anthoschmidtia of Africa. It differs from the first in the several- flowered spikelets that separate between the florets and in the awns interspersed with awned teeth. Anthoschmidtia differs in having glumes longer than the florets and in having lemmas with five awns alternating with four lobes. Cottea pappophoroides Kunth (fig. 40) is not abundant enough to have agricultural importance in the United States. Cleistogenes are produced in the lower sheaths. 1 32. PAPPOPHORUM Schreb. Spikelets 2 to 5 flowered, the upper reduced, the rachilla disarticu- lating above the glumes but not between the florets, the internodes very short; glumes nearly equal, keeled, thin-membranaceous, as long as or longer than the body of the florets, 1 to several nerved, acute; lemmas rounded on the back, firm, obscurely many nerved, dissected above into numerous spreading scabrous or plumose awns, the florets falling together, the awns of all forming a pappuslike crown ; palea as long as the body of the lemma, 2-nerved, the nerves near the margin. Erect, cespitose perennials, with narrow or spikelike tawny or purplish panicles. Species 20, in the dry parts of the Old World, in Australia, and from Texas to Argentina; 3 species in the United States, from Texas to Arizona. Type species: Pappophorum alopecuroideum Vahl. Pappophorum Schreb. ; Vahl, Symb. Bot. 3 : 10. 1794. Only one species de- scribed. Enneapogon Desv. ; Beauv., Ess. Agrost. 81, pi. 16, f. 11. 1812. Beauvois men- tions Enneapogon desvauxii, Pappophorum gracile, P. nigricans, P. pallidum, and P. purpurascens. The first one, being figured, is selected as the type. Polyrhaphis (Trin.) Lindl., Veg. Kingd. 115. 1847. Based on Pappophorum, section Polyrhaphis Trin., under which a single species, P. alopecuroides Vahl, is included. Pappophorum bicolor Fourn., with purplish, rather loose panicles, is found in southern and western Texas ; P. vaginatum Buckl. (fig. 41) , with pale, slender, spikelike panicles, and P. wrightii S. Wats. (fig. 42), with plumbeous short spikelike panicles and 9-nerved lemma, the nerves extending into 9 equal plumose awns, are found from western Texas to southern Arizona. Pappophorum wrightii produces cleis- togamous spikelets in the lower sheaths. The cleistogenes are larger than the normal florets, but the awns are almost wanting. As is the 1 Chase, Amer. Journ. Bot. 5 : 256. 1918. 84 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. PIG. 40. Cottea pappophoroides. Plant, X \ ; spikelet, floret, and cleistogene (left) from axil of lower leaf, all X 5. GENERA OF GRASSES OF THE UNITED STATES. 85 FIG. 41. Pappophorum vayinatum. Plant, X i ; spikelet and perfect floret, X 5. 86 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. case with other grasses producing cleistogenes in the lower sheaths, the culms disarticulate at the lower nodes. Our species are of minor FIG. 42. Pappophorum wriglitii. Plant, X \ ; spikelet, perfect floret, and cleistogene (below) from axil of lower leaf, all X 5. agricultural importance, the second and third sometimes constituting a fair proportion of the forage on sterile hills. GENERA OF GRASSES OF THE UNITED BTATES. 87 3. HORDEAE, BARLEY TRIBE. 33. AGBOPYBON Gaertn. Spikelets several-flowered, solitary (or rarely in pairs), sessile, placed flatwise at each joint of a continuous (rarely disarticulating) rachis, the rachilla disarticulating above the glumes and between the florets ; glumes two, equal, firm, several nerved, usually shorter than the first lemma, acute or awned, rarely obtuse or notched; lemmas convex on the back, rather firm, 5 to 7 nerved, usually acute or awned from the apex ; palea shorter than the lemma. Perennials or sometimes annuals, often with creeping rhizomes, with usually erect culms and green or purplish, usually erect spikes. Species about 60, in the temperate regions of both hemispheres ; about 25 species in the United States. Type species: Agropyron triticeum Gaertn. Agropyron Gaertn., Nov. Comm. Acad. Sci. Petrop. 14: 539, pi. 19, f. 4. 1770. Gaertner describes two species, A. cristatum, based on Bromus cristatus L., and a new species, A. triticeum. The second species is figured. The species are referred by some authors to Triticum. Some adopt the spelling Agropyrum. The two original species of Agropyron are annuals, but all the North American species are perennials. Nine of our species produce creeping rhizomes. One of these is the well-known quack-grass or couch-grass (A. repens (L.) Beauv.) (PI. IX; fig. 43), introduced from Europe. On account of its rhizomes, it is a troublesome weed in fields and meadows. Quack-grass can be distinguished by the glabrous, awnless or short-awned lemmas, awn-pointed glumes, thin, flat, usually sparsely pilose blades, and the yellowish rhizomes. An allied native species, A. smitJiii Hydb., differs in its pale rhizomes and its firm glaucous blades, soon involute in drying, the nerves prominent on the upper side. This species, called western wheat- grass and bluestem, is common west of the Mississippi River, where it is one of the most important native forage grasses. Another com- mon species of this group is A. dasystachyum (Hook.) Scribn. (in- cluding A. sulvillosum (Hook.) E. Nels.), found along the Great Lakes and westward. Of the species without rhizomes seven have awnless or short-awned lemmas. The commonest species of this group is A. tenerum Yasey, called slender wheat-grass. This is an erect grass 2 to 4 feet high, with flat blades and slender spikes, the broad glumes nearly as long as the spikelet. It ranges from New England to Washington, and southward in the Western States to Mexico. Slender wheat-grass is an excellent forage grass and produces a good quality of hay. The seed is offered by a few western seedsmen. This species is the only native grass that has been successfully cultivated and whose seed is on the market. 88 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. One of the long-awned species, Agropyron spicatum (Pursh) Scribn. and Smith (A. divergent Nees), called bunch-grass, or more distinctively blue bunch wheat- grass, is of especial value as a forage grass. It is 6ommon in the Columbia Basin, where it is one of the chief range grasses. The spe- cies is distinguished by its erect bunchy habit and by the spread- ing awns of the lemmas, giving the spike a bristly appearance. FIG. 43. Quack-grass, Ayropyron repens. Plant, X 1 ; spikelet, X 3 Two of our species have disarticulating spikes, thus approaching Sitanion. These are Agropyron saxicola (Scribn. and Smith) Piper, of Washington, and A. scribneri Vasey, a spreading mountain species Bui. 772, U. S. Dept. of Agriculture. PLATE IX. QUACK-GRASS (AGROPYRON REPENS). Bui. 772, U. S. Dept. of Agriculture. PLATE X. BOTTLE-BRUSH GRASS (HYSTRIX PATULA). A native species worthy of cultivation for ornament. GENERA OF GRASSES OF THE UNITED STATES. 89 found at altitudes of 12,000 to 14,000 feet. In some species there are two spikelets at the nodes of the rachis. This is especially frequent in A. smithii and allies it with Elymus. In general, all the species of Agropyron are forage grasses. They form an important part of the forage on the western range and in the valleys often grow in sufficient abundance to produce hay. For a revision of the species of Agropyron found in the United States, see Scribner and Smith, U, S. Dept. Agr., Div. Agrost. Bull. 4:25-36. 1897. 34. TBITICUM L. Spikelets 2 to 5 flowered, solitary, sessile, placed flatwise at each joint of a continuous or articulate rachis, the rachilla disarticulating above the glumes and between the florets or continuous; glumes rigid, 3 to several nerved, the apex abruptly mucronate or toothed or with one to many awns; lemmas keeled or rounded on the back, many- nerved, ending in one to several teeth or awns. Annual, low or rather tall grasses, with flat blades and terminal spikes. Species about 10, southern Europe and western Asia; none in the United States except Triticum aestiwum, the cultivated wheat. Type species : Triticum aestivum L. Triticum * L., Sp. PI. 85, 1753 ; Gen. PI., ed. 5, 37. 1754. Linnaeus describes seven species, T. aestivum, T. hybernum, T. turgidum, T. spelta, T. monocoocum, T. repens, T. caninum. The citation in the Genera Plantarum is to Tournefort's figures 292 and 293 which represent, the first, beardless wheat, and the second, bearded wheat. These two forms, beardless and bearded, are named by Lin- naeus T. aestivum, the bearded wheat, and T, hybernum, the beardless wheat. Triticum aestivum is chosen as the type because it has priority of position in the Species Plantarum. Linnseus divides the genus into two groups, " annua " and " perennia." The latter group, including Triticwm repens and T. caninum, is now referred to Agropyron. Zeia Lunell, Amer. Midi. Nat. 4 : 225. 1915. Based on " Triticum spelta Linn." Agropyron Gaertn. is included in the genus proposed. The most important species of Triticum is the cultivated wheat, T. aestivum L. (T. vulgare Vill., T. satiwtm Lam.). A large number of varieties are in cultivation, some with smooth lemmas, some with velvety lemmas, some with long awns (fig. 44), some awn- less (fig. 44, A). Durum wheat and club wheat are races, each with several varieties. Triticum monococcum L., einkorn or 1-grained wheat, is grown sparingly in Europe. Triticum dicoccwm Schrank, emmer, is cultivated in this country as a forage plant. In emmer the axis breaks up into joints, each joint bearing a spikelet which re- mains entire, each floret permanently inclosing its grain. 2 1 In the Species Plantarum the word appears in the plural, Tritica, probably inadvert- ently. 2 For a classification of wheats, see Jessen, Deutschlands Graser 191, 1863; Kornicke, Handb. Getreidebaues 1: 40, 1885; Hackel in Engl. and Prantl, Pflanzenfam. II, 2: 80, 1887 ; True Grasses, translated by Scribner and Southworth, 180, 1890 ; Schulz, Mitt. Natf. Ges. Halle 1: 14. 1911. For an account of T. dicoccoides Korn., recently found by Aaronsohn on Mount Hermon, Palestine, see Aaronsohn, Verb. Zool. Bot. Ges. Wien 59: 485, 1909; U. S. Dept. Agr., Bur. PI. Ind. Bull. 180: 38, 1910; Cook, U. S. Dept. Agr., Bur. PI. Ind. Bull. 274. 1913. 90 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. FIG. 44. Wheat, Triticum aestivum. Plant with awned spikes (bearded wheat) and (A) a nearly awnless spike (beardless wheat), both X I ; spikelet and floret, X 3. GENERA OF GRASSES OF THE UNITED STATES. 91 35. SECALE L. Spikelets usually 2-flowered, solitary and sessile, placed flatwise against the rachis ; the rachilla disarticulating above the glumes and produced beyond the upper floret as a minute stipe ; glumes narrow, rigid, acuminate or subulate-pointed ; lemmas broader, sharply keeled, 5-nerved, ciliate on the keel and exposed margins, tapering into a long awn. Erect, mostly annual grasses, with flat blades and dense terminal spikes. Species five, in the temperate regions of Eurasia ; one species cultivated in the United States and frequently escaped along way- sides. Type species : Secale cereale L. Secale L., Sp. PI. 84, 1753 ; Gen. PI. 36. 1754. Linnaeus describes four species: S. cereale, S. villosum, S. orientale, and . creticum. The second species is now referred to Haynaldia, the third to Agropyron. The first species is chosen as the type, as it is a well-known economic species. Secale cereale (fig. 45), common rye, is cultivated extensively in Europe and to some extent in the United States for the grain, but here it is frequently grown as a forage crop. Rye is used for winter forage in the South and for fall and spring pasture in the inter- mediate region, and for green feed farther north. It is also used for green manure and as a nurse crop for lawn mixtures, especially on public grounds when it is desired to cover the ground quickly with a green growth. Cultivated rye probably has been developed from the wild perennial European species S. montanuwi Guss. In the wild species of Secale the rachis disarticulates, but in 8. cereale it is con- tinuous. 36. SCRIBNERIA Hack. Spikelets 1-flowered, solitary, appressed and lateral to the some- what thickened continuous rachis, the rachilla disarticulating above the glumes, prolonged as a very minute hairy stipe;- glumes equal, narrow,' firm, acute, keeled on the outer nerves, the first 2-nerved, the second 4-nerved; floret with short hairs at the base; lemma shorter than the glumes, membranaceous; rounded on the back, obscurely nerved, the apex shortly bifid, the lobes obtuse, the faint midnerve extending as a slender straight awn ; palea 2-nerved, about as long as the lemma. Low annual, with slender cylindric spikes. Species one. Type species : Lepturus bolanderi Thurb. Scribneria Hack., Bot. Gaz. 11: 105, pi. 5. 1886. One species described, based on Lepturus bolanderi Thurb. The single species, Scriltnerw "bolanderi (Thurb.) Hack. (fig. 46), is found in sandy sterile ground in the mountains from central California to Washington. It is too small and rare to be of economic importance. 92 BULLETIN 772, IT. S. DEPARTMENT OF AGRICULTURE. FIG. 45. Rye, 8ecale cereale. Plant, X i ; spikelet, X 3 ; floret showing rudiment back of palea, X 5. GENERA OF GRASSES OF THE UNITED STATES. 93 37. ELYMUS L. Spikelets 2 to 6 flowered, sessile in pairs (rarely 3 or more or soli- tary) at each node of a continuous rachis, the florets dorsiventral to the rachis; rachilla disarticulating above the glumes and between the florets; glumes equal, usually rigid, sometimes indurate below, nar- row, sometimes subulate, 1 to several nerved, acute to aristate, some- what asymmetric and often placed in front of the spikelets ; lemmas rounded on the back or nearly terete, obscurely 5-nerved, acute or usually awned from the tip. Erect, usually rather tall grasses, with flat or rarely convolute blades and ter- minal spikes, the spikelets usually crowded, some- times somewhat distant. Species about 45, in the temperate regions of the Northern Hemisphere; 25 species in the United States, most of them in the Western States. Type species : Elymus sibiri- cus L. Elymus L., Sp. PI. 88, 1753 ; Gen. PI., ed. 5, 36. 1754. Lin- naeus describes five species, E. arenarius, E. sibiricus, E. can- adensis, E. virginicus, and E. c U. 3. DEPARTMENT OF AGRICULTURE. FIG. 51. Hordeum nodosum. Plant, X I. ; group of three spikelets with rachis joint attached and a floret, the latter showing the rudiment back of the palea, X 3. GENERA OF GRASSES OF THE UNITED STATES. 103 Annuals or perennials, with flat blades and simple terminal flat spikes. Species about eight, in Eurasia, four of these being intro- duced in the United States. Type species : Lolium perenne L. Lolium L., Sp. PI. 83, 1753 ; Gen. PL, ed. 5, 36. 1754. Linnaeus describes two species, L. perenne and L. temulentum. The first is chosen as the type, as it is an economic species. Both were described in the flora of Sweden. Two species are of agricultural importance. Lolium perenne, Eng- lish or perennial rye-grass, was the first meadow grass to be culti- vated in Europe as a distinct segregated species, the meadows and pastures formerly being mixed native species. This and the next are probably the most important of the European forage grasses. Eng- lish rye-grass is a biennial or short-lived perennial, 2 to 3 feet tall, with glossy dark-green leaves and a slender spike as much as a foot long, the spikelets 8 to 10 flowered, somewhat longer than the glume, the lemmas awnless. Italian rye-grass, L. multiflorum Lam. (L. itali- cum A. Br.) (PL XI; fig. 52), differs from the preceding in having awned lemmas and usually a greater number of florets to the spikelet. Both species are used to a limited extent for meadow, pasture, and lawn. They are of some importance in the South for winter forage. Lolium multiftorum is common in the humid region of the Pacific coast, where it is often called Australian rye-grass. In the Eastern States the rye-grasses are often sown in mixtures for parks or public grounds, where a vigorous early growth is re- quired. The young plants can be distinguished from bluegrass by the glossy dark-green foliage. Lolium temulentum L., darnel, is occasionally found as a weed in grain fields and waste places. It is in bad repute, because of the pres- ence in the fruit of a narcotic poison, said to be due to a fungus. Dar- nel is supposed to be the plant referred to as the tares sown by the enemy in the parable of Scripture. It is an annual, with glumes as much as an inch long and exceeding the 5 to 7 florets. 42. LEPTURUS R. Br. (Monerma Beauv.) Spikelets 1-flowered, embedded in the hard, cylindric, articulate rachis, placed edgewise thereto, the first glume wanting except on the terminal spikelet, the second glume closing the cavity of the rachis and flush with the surface, indurate, nerved, acuminate, longer than the joint of the rachis ; lemma lying next the rachis, hyaline, shorter than the glume, 3-nerved ; palea hyaline, 2-nerved, a little shorter than the lemma; rachilla not disjointing, the spikelet falling entire, at- tached to its rachis joint. Low annuals or perennials, with hard cylindric spikes. Species three, all from the Eastern Hemisphere, one introduced in California. 104 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. FIG. 52. Italian rye-grass, Lolium multifiorum. Plant, X I ; spikelet, X 3 ; floret, X 5. Bui. 772, U. S. Dept. of Agriculture. PLATE XI, ITALIAN RYE-GRASS (LOLIUM MULTIFLORUM). Bui. 772, U. S. Dept. of Agriculture. PLATE XII. TALL OAT-GRASS (ARRHENATHERUM ELATIUS). GENEKA OF GRASSES OF THE UNITED STATES. 105 Type species : Rottboellia repcns Forst. Lepturus R. Br., Prodr. Fl. Nov. Holl. 207. 1810. One species described L repens, based on Rottboellia repens Forst. Monerma Beauv., Ess. Agrost. 116, pi. 20, f. 10. 1812. The species figured is M . monandra, which is Lepturus cylindrica. Leptocercus Raf., Amer. Monthly Mag. 4: 190. 1819. In a review of Nuttall's Genera Rafinesque changes the name Lepturus R. Br. to Leptocercus because of a genus of insects by the name of Leptura. Our one species, Lep- turus cylindrica (Willd.) Trin. (fig. 53), is intro- duced in salt marshes from San Francisco to San Diego. At matur- ity the spike breaks up into the 1 -seeded joints. The species has no eco- nomic value. For other species that have been referred to Lepturus. see Pholiurus. 43. PHOLIURUS Trin. (Lepturus of authors, not R. Br.) Fie. ^.-Lcvturus cylinartca. Plant, X 1' ^pikelets 1 or 2 HOW- spikelet with a joint of the rachis, x 5 ; spike- erecl ? embedded in the let, front view, x 5. articulate rachis and falling attached to the joints; glumes two, placed in front of the spikelet and inclosing it, coriaceous, 5-nerved, acute, asymmetric, 106 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. appearing like halves of a single split glume ; lemma lying next to the axis, smaller than the glumes, hyaline, keeled, scarcely more than 1-nerved ; palea a little shorter than the lemma, hyaline, 2-nerved. Low annuals, with cylindric spikes. Species four, in the Eastern Hemisphere, one introduced into the United States. Type species : Roffboellia pannonica Host. Pholiurus Trin., Fund. Agrost. 131. 1820. Based on a single species. Rott- boellia pannonica Host. This species has 2-flowered spikelets. Lepiurus Dumort., Obs. Gram. Beige 140, pi. 15, f. 57. 1823. A single species based on " Rottbolia incurvata L." fils. The species of Pholiurus have been referred by most recent authors to Lepturus, the type of which was, by the same authors; referred to Monerma. Our species, Pholiurus incurvatus (L) . Hitchc. (Aegilops incurvata L., 1 Lep- turus filiformis (Eoth.) Trin.) (fig. 54), has 1-flowered spikelets. It is intro- duced along the borders of salt marshes FIG. 54. Pholiurus incur vatuti. Plant, x i ; spikelet with a joint of the rachis, X 5 ; spikelet, front view, X 5. from Maryland to Virginia and from Marin County to San Diego, Calif. It has no economic value. 4. AVENEAE, THE OAT TRIBE. 44. KOELERIA Pers. Spikelets 2 to 4 flowered, compressed, the rachilla disarticulating above the glumes and between the florets, prolonged beyond the per- fect florets as a slender bristle or bearing a reduced or sterile floret at the tip ; glumes usually about equal in length but unequal in shape, the lower narrow and sometimes shorter, 1-nerved, the upper some- what broader above the middle, wider than the lower, 3 to 5 nerved ; 1 Sp. PI. ed. 2. 2: 1490. 1763. GENERA OF GRASSES OF THE UNITED STATES. 107 lemmas somewhat scarious and shining, the lowermost a little longer than the glume, obscurely 5-nerved, acute or short-awned, the awn, if present, borne just below the apex. Annual or perennial," slender, low or rather tall grasses, with nar- row blades and spikelike panicles. Species about 20, in the temperate regions of both hemispheres; two species in the United States, one native and one introduced. Type species : Aira cristata L. Koeleria Pers., Syn. PI. 1 : 97. 1805, Persoon describes five species, K. yra- cilis, K. cristata, K. tuberosa, K. phleoides, and K. villosa. Of these, K. cristata and K. phleoides were described by Linnaeus, the first under Aira, the second under Festuca. The first of these is selected as the type, as it has priority of position in the Species Plantarum. Airochloa Link, Hort. Berol, 1 : 126. 1827. Six species are included. Koeleria cristata, upon which the first species is based, is taken as the type. Brachystylus Dulac, Fl. Hautes Pyr. 85. 1867. Based on " Koeleria Pers." Recently a monograph of Koeleria was published by Domin 1 in which many species were described. Several of these were based upon material from the United States but appear to be only forms of the widely distributed K. cristata. Koeleria cristata (L.) Pers. (fig. 55) is the only species native in North America. This is a common constituent of grassland on prai- ries, plains, and in open woods from Ontario to British Columbia and south to northern Mexico. It is a cespitose perennial, with slender, erect culms a foot or two high, with a pale, shining, densely flowered panicle 2 to. 5 inches long. The species varies much, but the forms, except K. cristata longifolia Yasey, of California, with longer blades and larger, more open panicles, can not be distinguished as varieties. The slender form, of the semiarid plains and foothills of the West, is held by some as distinct and called K. grocilis Pers. The spikelets of K. cristata are mostly 2 or 3 flowered, with a slender prolongation of the rachilla, and the lemmas are acute or mucronate, but not awned. The habit suggests a species of Poa, from which genus it is distinguished by its mostly 2 or 3 flowered spikelets, acute lemmas, and the culm puberulent below the panicle. A second species, K. phleoides (Vill.) Pers., a low annual with short-awned lemmas, is introduced from Europe in a few localities. Hackel (Nat. Pfl anzenf am. ) places Koeleria in the FestuceaB, but South American and Old World species of Koeleria, with lemmas awned below the apex, as well as the shining culm and spikelets of K. cristata^ show clearly an affinity to Trisetum. For this reason the genus is here placed in Aveneae, although the glumes do not exceed the florets as they do in nearly all the Aveneae. Koeleria cristata is a good forage grass and is a constituent of much of the native pasture throughout the Western States. 45. TRISETUM Pers. Spikelets usually 2-flowered, sometimes 3 to 5 flowered, the rachilla prolonged behind the upper floret, usually villous ; glumes somewhat 1 Monographic der Gattung Koeleria. 1907. 108 BULLETIN 772, TJ. S. DEPARTMENT OF AGRICULTURE. unequal, acute, awnless, the second usually longer than the first floret; lemmas usually short-bearded at the base, 2-toothed at the apex, the teeth often awned, bear- ing from the back below the cleft apex a straight and in- cluded, or usually bent and ex- serted, awn. Tufted perennials with flat blades and open or usually con- tracted or spikelike panicles. Species about 65, in the arctic and temperate regions of both hemispheres ; eight species in the United States, mostly in the mountains. Type species : Arena flavescens L. Trisetum Pers., Syn. PI. 1: 97. 1805. Persoon describes 11 species. The seventh species, T. pratense Pers., based on Avena flavescens L., is chosen as the type, because it is historically the oldest species. Graphephorum Desv., Nouv. Bull. Soc. Philom. Paris 2: 189. 1810. Based on Aira melicoides Michx. The name Trisetum refers to the three awns on the lemma of many of the species, one from the back and one from each of the teeth. In two of our species, T. melicoideum (Michx.) Scribn. and T. wolfii Vasey, the awn from the back is included within the glume or is wanting. Trise- tum spicatum (L.) Eichter (fig. 56) is found at high altitudes in all the western mountains and is widespread at high altitudes and in the arctic regions of the North- ern Hemisphere. It is an erect grass with a spikelike, often dark-colored panicle, the awn exserted and bent. Trisetum canes cens BuckL, of the Western States, is a woodland grass with narrow but rather loose panicles. Trisetum cernuum Trin., of the Northwest, has broad flat blades and a loose open penicle, with lax FIG. 55. Koeleria cristata. spikelet and floret, Plant, X 5. X I GENERA OF GRASSES OF THE UNITED STATES. 109 drooping branches, the florets distant in the usually 3-flowered spike- lets. Trisetum pennsylvanicum (L.) Roem. and Schult. (Sphenopholis palustris (Michx.) Scribn.), T. hallii Scribn., and T. inter- ruptum Buckl. have been referred to Sphenopholis. I n the first, the upper lemma is slightly bearded at base, the lower glabrous ; in the other two, the lemmas are glabrous. In these three species the articulation is be- low the spikelet, as in Sphenopholis, for which reason Scrib- ner placed them in that genus, but their a w n e d, relatively thin lemmas and their glumes alike in shape place them more naturally in Trisetum. FIG. 56. Trisetum spicatum. Plant, X I ; spikelet and floret, X 5. The species of Trisetum are all valuable for grazing. Trisetum spicatum constitutes an important part of the forage on alpine slopes. 110 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. 46. SPHEXOPHOLIS Scribn. (Eatonia of authors, not Raf.) Spikelets 2 or 3 flowered, the pedicel disarticulating below the glumes, the rachilla produced beyond the upper floret as a slender bristle ; glumes unlike in shape, the first narrow, acute, 1-nerved, the second broadly obovate, 3 to 5 nerved, somewhat coriaceous; lemmas firm, scarcely nerved, awnless, the first a little shorter or a little longer than the second glume. Perennial grasses, with usually flat blades and narrow panicles. Species four, in the United States, extending into Mexico and the West Indies. Type species: Aim obhifuita Miehx. Reboulea Kunth, Rev. Gram. 1: 341, pi. 84, 1830, not Rebouillia Raddi, 1818. A', gracilis, the only species described, is the same as Aira obtusata Michx. Colobanthus (Trin.) Spach. Suites Buff. 13: 163, 1846, not Bartl., 1830. Trinius applied the name to a section of Trisetum. The type is Koeleria penn- sylvanica DC. (Sphenopholis pallens), the first of two species mentioned by Trinius, the other being Aira obtiisata Michx. Sphenopholis Scribn., Rhodora 8 : 142. 1906. A new name is proposed for the group of grasses then known as Eatonia, and the type species is designated. Scribner showed that the original description of Eatonia Raf. could not apply to the genus as later described by Endlicher. 1 The type species of Eatonia Raf. proves to be Panicum virgatum. 2 The genus Sphenopholis was revised by Scrib- ner in the above-mentioned paper. One species, Sphenopholis obtwata (Michx.) Scribn. (fig. 57), is widespread, but not very abundant, throughout the eastern half of the United States. In the western portion of its range the panicle is condensed and spikelike (var. lolata (Trin.) Scribn.). All the species are forage grasses, but they are usually not abundant enough to be of much importance. 47. AVENA L., oats. Spikelets 2 to several flowered, the rachilla bearded, disarticulating above the glumes and between the florets ; glumes about equal, mem- branaceous or papery, several-nerved, longer than the lower floret, usually exceeding the upper floret ; lemmas indurate, except toward the summit, 5 to 9 nerved, bidentate at the apex, bearing a dorsal bent and twisted awn (this straight and reduced in Avena sativa). Annual or perennial, low or moderately tall grasses, with narrow or open, usually rather few-flowered panicles of usually large spikelets. Species about 55, in the temperate regions; only a few in the Western Hemisphere; 7 species in the United States, only 2 being native. Type species : Avena sativa L. Avena L., Sp. PI. 79, 1753; Gen. PI., ed. 5, 34. 1754. Linnaeus describes 10 species, 3 of which are now retained in Avena. These are A. sativa, A. fatiia, and A. pratensis. The other species are now referred as follows : A. sibirica to . PI. 99. 1837. 2 Hitchcock, Contr. U. S. Nat Herb. 15:87. 1910. GENERA OF GRASSES OF THE UNITED STATES. Ill Stipa, A. elatior to Arrhenatherum, A. pennsylvanica to Trisetum, A. flavescens to Trisetum, A. fra'gilis to Gaudinia, A.,spicata to Danthonia. In the Genera FIG. 57. Sphenopholis obtusata. Plant, X i ; spike- let and floret, X 5. Plantarum, Linnaeus cites Tournefort's figure 26 f (error for 297), which is Avena sat iva,. Hence this is the type species. The most impor- tant species of the genus is Avena sativa, the familiar culti- vated oat. In many of the varieties the awn is straight, often reduced, or even want- ing. The spikelets contain usually two florets that do not easily disarticulate. The lemmas are smooth or slightly hairy at the base, the apical teeth acute but not awned. The grain is permanently in- closed in the lemma and palea. Two other introduced species are known as wild oats, because of their close resemblance to the cultivated oat. Avena fatua L. (fig. 58) dif- fers from A. sativa in the readily disar- ticulating florets, be- set with stiff, usually brown hairs, and in he well-developed . . J geniculate and twisted awn. A variety of this (A. fatua glalrata Peterm.) has glabrous 112 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. florets. In our other species of wild oats, A. barbata Brot., the pedicels are more slender, the spikelets pendulous, and the teeth of FIG. 58. Wild oats, Avena fatua. Plant, X I ; spikelet and floret, X 2. the lemma are prolonged into delicate awns. These species of wild oats are common on the Pacific coast, where they are weeds, but are GENEKA OF GRASSES OF THE UNITED STATES. 113 utilized for hay. Much of the grain hay of that region is made from either cultivated or wild oats. The varieties of cultivated oat are derived from three species of Avena. The common varieties of this country and of temperate and mountain regions in general are derived from A. faitua. The Algerian oat grown in North Africa and Italy and the red oat of our Southern States are derived from A. sterUis. A few varieties adapted to dry countries are derived from A. bar'bata'*-. Avena sterilis L., animated oats, is sometimes cultivated as a curiosity. When laid on the hand or other moist surface the fruits twist and untwist as they lose or absorb moisture. Our two native species, found in the Rocky Mountain region, are perennials, with narrow few-flowered panicles of erect spikelets smaller than those of Avena sativa. They are excellent forage grasses, but occur only scatteredly. 48. AREHENATHERUM Beauv. Spikelets 2-flowered, he lower floret staminate, the upper perfect, the rachilla disarticulating above the glumes, produced beyond the florets as a slender bristle ; glumes rather broad and papery, the first 1-nerved, the second a little longer than the first and about as long as the spikelet, 3-nerved; lemmas 5-nerved, hairy on the callus, the lower bearing near the base a twisted, geniculate, exserted awn, the upper bearing a short, straight, slender awn just below the tip. Perennial, rather tall grasses, with- flat blades and rather dense panicles. Species about six, in the temperate regions of Eurasia; ' one species introduced into the United States. Type species : Arrhenatherum avenaceum Beauv. Arrhenatherum Beauv., Ess. Agrost. 55, pi. 11, f. 5. 1812. Beauvois figures one species, which he calls Arrhenatherum avenaceum. This is Avena elatior L., and is now called Arrhenatherum elatius (L.) Mert. and Koch. Arrhenatherum elatius (PI. XII; fig. 59) is occasionally cultivated in the humid regions of the United States as a meadow grass under the name of tall oat-grass. It is a fairly satisfactory forage grass, but the seed is expensive and often of poor quality. This species is often found growing spontaneously* in grassland and along road- sides in the Northern States. A variety, Arrhenatherum elatius bulb o sum (Presl) Koch, has ap- peared recently in some of the Atlantic States. It differs from the ordinary form in having at the base of the stem a moniliform string of 2 to 5 small corms 5 to 10 mm. in diameter. 1 See Journ. Hered, 5 : 56, 1914, a translation of an article by Trabut. Also see Norton, Amer. Breed. Assoc. 3: 281. 1907. 97769 19 Bull. 772 8 114 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. 49. AIRA L. (Descliampsia Beauv.) Spikelets 2-flowered, disarticulating above the glumes, the hairy rachilla prolonged behind the upper floret as a stipe, this sometimes bearing a reduced floret; glumes about equal, acute or acutish, membranaceous ; lemmas thin, truncate and 2 to 4 toothed at the summit, bearing a slender awn from or below the middle, the awn straight, bent, or twisted. Low or moderately tall annual or usually peren- nial grasses, with shining pale or purplish spikelets in narrow or open pani- cles. Species about 35, in the temperate and cool regions of both hemispheres, 6 of these being in the United States. Type species : Aira caespitosa L. Aira L., Sp. PI. 63, 1753 ; Gen. PI., eel. 5, 31. 1754. Fourteen species are described. The name was first used for a genus by Linnaeus in his Flora Lapponica in 1737, where he describes four species. These four species are named in the Species Plantarum : 7. A. spicata, 8. A. caespitosa, 9. A. flexuosa, 10. A. montana. The first of these, A..spicata, is referred to Trisetum ; the other three be- long to Deschampsla, as recognized in most American botanies. The genus Aira, as accepted by Bentham and Hooker in the Genera Plantarum and by Hackel in the Natiirlichen Pflanzenfamilien, is based upon the last two of the original Linnseari FIG. 59. Tall oat-grass, Arrhenathcrum elatius. Plant, X i ; spikelet and fertile floret, X 5. GENERA OF GRASSES OF THE UNITED STATES. 115 FIG. 60, Tufted hair-grass, Aira caespitosa. Plant, X ; spikelet and two views of floret, X 5. 116 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. species, A. praecox and A. caryophyUca, which are found in southern Europe and are not described by Linnaeus in his Flora Lapponica nor in his Flora Suecica. Linnseus's generic idea of Aira is evidently represented by the four species first included in the genus. From these Aira caespitosa is arbitrarily selected as the type. Deschampsia Beauv., Ess. Agrost. 91, pi. 18, f. 3. 1812. The figured species, the type, is D. caespitosa. Lerchenfeldia Schur., Enum. PI. Transs. 753. 1866. Three species are in- cluded. Aira flexuosa L., on which L. flexuosa is based, is taken as the type. Aira danthonioides Trin. of the Pacific coast is an annual. Aira caespitosa L. (Deschampsia caespitosa Beauv.) (fig. 60) is common in moist or wet soil from Newfoundland to Alaska and south to New Jersey, Illinois, and, in the western mountains, to New Mexico and southern California. It is a tufted perennial 1 to 4 feet high, with smooth, narrow, folded blades and open drooping panicles, 4 to 12 inches long, of shining pale-bronze or purplish spikelets. This spe- cies, sometimes called tufted hair-grass, is often the dominant grass in mountain meadows, where it furnishes excellent forage. 50. ASPEIS Adans. (Aira of authors.) Spikelets 2-flowered, the rachilla disarticulating above the glumes, not prolonged; glumes about equal, acute, membranaceous or sub- scarious ; lemmas firm, rounded on the back, tapering into two slender teeth, the callus with a very short tuft of hairs, bearing on the back below the middle a slender, geniculate, twisted, usually exserted awn, this reduced or wanting in the lower floret in one species. Low, delicate annuals with small open or contracted panicles. Spe- cies about nine, in southern Europe, three being introduced in the United States. Type species : Aira praecor L. Aspris Adans., Fam. PL 2: 496, 522. 1763. The references cited are also cited by Linnseus under Aira praecox. Caryophyllea Opiz, Seznam 27. 1852. Based on Aira caryophyllea. Fussia Schur., Enum. PI. Transs. 754. 1866. Three species, F. praecox, F. caryophyllea, and F. capillaris, are included. Aira praecox, upon which the first species is based, is taken as the type. Our three species are Aspris caryopJiyllea (L.) Nash (fig. 61), A. praecox (L.) Nash, and A. capillaris (Host) Hitchc. ( Aira capillaris Host) . They are found frequently on the Pacific coast and occasion- ally in the Eastern States. The species are of no economic importance. Weingaertneria canescens Bernh. has been found upon ballast at Philadelphia and on Marthas Vineyard. This is a low, tufted annual with pale, contracted panicles, differing from the species of Aspris in having club-shaped awns. 51. NOTHOLCUS Nash. (Holcus of authors.) Spikelets 2-flowered. the pedicel disarticulating below the glumes, the rachilla curved and somewhat elongate below the first floret, not prolonged above the second floret; glumes about equal, longer than GENERA OF GRASSES OF THE UNITED STATES. 117 the two florets; first floret perfect, its lemma awnless; second floret staminate, its lemma awned on the back. FIG. 61. Aspris caryopliyllea. Plant, X 1 ; spikelet and two views of floret, X 5. Perennial grasses, with flat blades and contracted panicles. Species about eight, Europe and Africa; two introduced into the United States. Type species : Holcus lanatus L. Ginannia Bubani, Fl. Pyren. 4: 321, 1901, not Scop., 1777, nor Dietr., 1804. P.ased on " Holcus L. et Auctor.," the two species included, G. pubesccns and O. molli-x, showing that it is to the species congeneric with Holcus lanatus L. that the name is applied. 118 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. Notholcus Xash; Hitch., in Jepson, Fl. Calif. 3: 128. 1912. Only one species described. Notholcus is derived from the Greek nothos, false, and Holcus, the generic name formerly applied to this group. Nash 1 spells the name Nothoholcus. For a discussion of the reasons for the change of name, see page 266. The ge- neric name Holcus is there applied to the sorghums, necessitating a new name for the velvet grass. The common species in the United States is Notholcus lanatus (L.) Nash (Holcus lanatus L.), known as velvet grass (fig. 62). This species is introduced in various places in the Eastern States and also on the Pacific coast, where it is abundant. It is an erect, grayish, velvety-pubescent grass 2 to 3 feet tall, with a contracted pale or purplish panicle 2 to 4 inches long. Velvet grass is some- times recommended as a meadow grass, but for this purpose it has little value except on moist sandy or sterile soil where other grasses will not thrive. It has been used with some success in sandy fields around the mouth of the Columbia River in Washington and Oregon. A second species, Notholcus mollis (L.) Hitchc., with creeping rhizomes, has been introduced in California, where it is rare. 52. DANTHONIA Lam. and DC. Spikelets several-flowered, the rachilla readily disarticulating above the glumes and between the florets ; glumes about equal, broad and papery, acute, mostly exceeding the uppermost floret; lemmas rounded on the back, obscurely several-nerved, the base with a strong callus, the apex bifid, the lobes acute, usually extending into slender awns, a stout awn arising from between the lobes ; awn flat, tightly twisted below, geniculate, exserted, including three nerves of the lemma. Tufted, low or moderately tall perennials, with few-flowered, open, or spikelike panicles of rather large spikelets. Species about 100, in the temperate regions of both hemispheres; especially abundant in South Africa ; 12 species in the United States, about equally divided between the Eastern and the Western States. Type species : Avena spicata L. Danthonia Lam. and DC., Fl. Franc. 3: 32. 1805. The work cited is a local flora in which the two French species are described, D. decumbent (which is the same as Xicfillnyia (lecuiubcnx) and D. prorincialis. The authors, however, mention in the paragraph preceding the one devoted to the generic description that "besides the species described below one ought to refer to this genus, 1st, Avena spicata L. or Avena ylumosa Michx. ; 2d, Arena cfilicina Lam. not Vill." Of the four species mentioned, three are congeneric with Avena spicata and correspond with the generic description better than does Danthonia decumbens, which is the first species described under Danthonia. Avena spicata is se- lected as the type of Dauthonia. 2 Piper 3 has selected Festuca decumbens L. (Danthonia decumbens) as the type of Danthonia because it is the first species described under Danthonia, and takes up Merathrepta Raf. for the species generally referred to Danthonia. Nelson and Macbride 4 take up Pentameris Beauv. in place of Merathrepta. iBritt. and Brown, Illustr. Fl., ed. 2. 1: 214. 1913. 2 See Hitchc., Bot. Gaz. 57 : 328. 1914. sContr. T T . S. Xat. Herb. 11: 122. 1906. *Bot. Gaz. 56: 469. 1913. GENERA OF GRASSES OF THE UNITED STATES. 119 PIG. 62. Velvet grass, Xotliolcns la nut us. Plant, X l; spikelet, florets with glumes removed, arid mature fertile floret, all X 5. 120 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. Pentameris Beauv., Ess. Agrost. 92, pi. 18, f. 8. 1812. P. tlmarii is the type, as this is the single species mentioned and figured. This is a South African species and represents a group in which the lateral teeth of the lemmas are 2-awned. The group is considered to be generically distinct from Dan- thonia by Stapf. 1 The name is taken up by Nelson and Macbride in place of Merathrepta Raf. 2 Merathrepta Rat, Bull. Bot. Seringe 1: 221. 1830. The genus is described briefly and Arena spicata mentioned. This species is, therefore, the type. One species of Danthqnia, D. spicata (L.) Beauv. (fig. 63), is common on sterile hills and in dry, open woods in the Eastern States, where it is sometimes called poverty grass. It can be recognized, even when not in flower, by its small tufts of curly leaves. In the Western States the species are found in grass- land and contribute somewhat toward the forage value of the range, but usually they are not abundant. All our species pro- duce cleistogenes (enlarged fer- tile cleistogamous spikelets) in the lower sheaths, 3 and the culms finally disarticulate at the nodes below these. FIG. G3. Wild oat-grass, Danthonia spicata. Plant, X I ', spikelet, floret, and a cleisfo- gene from the axil of a lower leaf, all X 5. 1 Thiselt. Dyer, Fl. Cap. 7 : 512. 1898. 2 See following paragraph on Merathrepta. 3 Chase, Amer. Journ. Bot. 5:254. 1918. GENERA OF GRASSES OF THE UNITED STATES. 121 5. AGROSTIDEAE, THE TIMOTHY TRIBE. 53. CALAMAGROSTIS Adans. Spikelets 1-flowered, the rachilla disarticulating above the glumes, usually prolonged behind the palea as a short, commonly hairy bristle ; glumes about equal, acute or acuminate; lemma shorter and usually more delicate than the glumes, the callus bearing a tuft of hairs, which are often copious and as long as the lemma, awned from the back, usually below the middle, the awn being delicate and straight, or stouter and exserted, bent and sometimes twisted; palea shorter than the lemma. Perennial, usually moderately tall or robust grasses, with small spikelets in open or usually narrow, sometimes spikelike panicles. Species over 100, in the cool and temperate regions of both hemi- spheres ; 26 species in the United States, mostly in the western moun- tains. Type species: Arundo calamagrostix L. Calamagrostis Adans., Fam. PI. 2: 31, 530. 1763. Adanson describes no species but in the index there is given under Kalamagrostis Diosk., three names or citiations, Negil. Arab., Gramen. Sheuz. t. 3. f. 5., and Arundo Lin. The reference to Scheuchzer is found in Linnseus's Species Plantarum under Arundo calamagrostis (1: 82), which consequently is the type of Calamagrostis. Deyeuxia Clarion; Beauv., Ess. Agrost. 43, pi. 9, f. 9, 10. 1812. Type, D. montana, the first of the two species figured. Amagris Raf., Princip. Fondarnent. Somiologie 27. 1814. A new name pro- posed for Calamagrostis, because that is formed of two other names. Athernotus Dulac, Fl. Hautes Pyr. 74. 1867. Based on " Calamagrostis Ad." Lunell * uses this name for Calamovilfa, but Dulac bases the genus on Cala- magrostis Adans., and the three species he includes belong in Calamagrostis, not in Calamovilfa. By some authors the species with prolonged rachilla are segregated as a distinct genus, Deyeuxia, the name Calamagrostis being retained for those species in which the rachilla is not prolonged. The Ameri- can species all belong to the section Deyeuxia. Four Pacific coast species have loose, open panicles. In all the other species the panicle is rather compact, in some cases spikelike. The commonest species in the United States is CaZaanagrostis cana- densis (Michx.) Beauv. (fig. 64), growing in swamps and low ground from New England to Oregon, and southward in the mountains and northward to the arctic circle. It is an important source of wild hay from Wisconsin to North Dakota, but is of only medium value for grazing. Much of the marsh hay of Wisconsin and Minnesota be- longs to this species, which in that region is called blue joint. This is the dominant grass in the interior of Alaska. The species is distin- guished by having flat blades, a somewhat lax, usually nodding panicle, the hairs at the base of the floret copious and as long as the lemma, the awn straight, delicate, not exserted beyond the glumes, the latter 3 to 5 mm. long. i Amor. Midi. Nat. 4: 218. 1915. 122 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. FIG. G4. Bluojoint, Cala-mauruatis canadcnais- Plant, X \ ; spikelet and floret, X 5. GENERA OF GRASSES OF THE UNITED STATES. 123 C alamagrostis scabra Presl, closely allied to the above, but with somewhat larger spikelets, is abundant along the coast from Oregon to Alaska. This has been incorrectly referred to C. langsdorfii (Trin.) Link, of Siberia. In general, the species of Calamagrostis are important forage grasses. Pine-grass (C. rubescens Buckl.) is common in the mountains of Oregon and Washington, where it forms an important part of the forage. For a revision of the species of Calamagrostis found in the United States, see Kearney, U. S. Dept. Agr., Div. Agrost. Bull. 11. 1898. 54. AMMOPHILA Host. Spikelets 1 -flowered, compressed, the rachilla disarticulating above the glumes, produced beyond the palea as a short bristle, hairy above; glumes about equal, chartaceous ; lemma similar to and a little shorter than the glumes, the callus bearing a tuft of short hairs ; palea nearly as long as the lemma. A tough, rather coarse, erect perennial, with hard, scaly, creeping rhizomes, long, tough, involute blades, and a pale, dense, spikelike panicle. One species is found on the sandy seacoast of Europe and northern .North America as far south as North Carolina and on the shores of the Great Lakes, a second species around the Baltic. Type species: Arundo arenaria L. Ammophila Host, Gram. Austr. 4: 24, pi. 41. 1809. Only one species de- scribed. A. anmdinacea Host, based on Arundo arenaria L. Psamma Beaiiv., Ess. Agrost. 143, pi. 6, f. 1. 1812. The one species, P. Uttoralis, is Ammophila arenaria. AmmopMla arenaria (L.) Link (fig. 65) is an important sand- binding grass in Europe, being used there to hold the barrier dunes along the coast. In this country it has been tried with success on Cape Cod and at Golden Gate Park, San Francisco. 1 It is called beach-grass and less frequently marram grass and sea marram. 55. CALAMOVILFA Hack. Spikelets 1-flowered, the rachilla disarticulating above the glumes, not prolonged behind the palea ; glumes unequal, acute, chartaceous ; lemma a little longer than the second glume, chartaceous, awnless, glabrous or pubescent, the callus bearded ; palea about as long as the lemma. Perennial, rigid, usually tall grasses, with narrow or open panicles, some species with creeping rhizomes. Species four, confined to the United States and southern Canada. Type species : Calam.agrostis brevipilis Gray. Calamovilfa Hack., True Grasses 113. 1890. The True Grasses is a transla- tion by Scribner and Southworth of the article on grasses in Engler and Prantl's Natiirliclien Pflanzenfamilien. Scribner has added bracketed notes. In a para- 1 For a full discussion, see Hitchcock, U. S. Dept. Agr., Bur. PI. Ind. Bull. 57 ; Westgate, U. S. Dept. Agr., Bur. PI. Ind. Bull. 05. 1904. 124 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. FIG. 65. Beach-grass, AmmopJiila arenaria. Plant, X J ; spikelet and floret, X 5. GENERA OF GRASSES OF THE UNITED STATES. 125 graph quoted from Hackel ("Hackel in MS.") is a statement that two species, Calamagrostis brevipilis Gray and C. longifolia Hook., may best be considered a separate g3iius, Calamovilfa. Scribner adds a note formally describing the genus Calamovilfa and mentions the two species, Calamovilfa brevipilis and C. longi- folia. The first is selected as the type. The genus differs from Calamagrostis in the chartaceous lemma, from our species of Calamagrostis in the absence of a prolonged ra- chilla, and from Ammophila in the more open panicles and in the absence of the prolongation of the rachilla. The four species are Calamovilfa brevipilis (Torr.) Scribn., in the pine barrens from New Jersey to North Carolina; C. curtissii (Vasey) Scribn., confined to Florida; C. longifolia (Hook.) Scribn. (fig. 66), of the Great Plains and the dune region of Lake Michigan; C. gigantea (Nutt.) Scribn. and Merr., also of the Great Plains. The first two species are without creeping rhizomes; the other two have numerous stout rhizomes and are excellent sand binders. Calamovilfa longifolia and C. gigantea are closely re- lated. They are differentiated by the less expanded panicle and glabrous florets of the first and the spreading panicle, larger spike- lets, and villous florets of the second. Calamovilfa longifolia, the commonest species, is of some value for forage, but is rather coarse and woody. 56. AGBOSTIS L., the bent-grasses. Spikelets 1-flowerecl, disarticulating above the glumes, the rachilla usually not prolonged; glumes equal or nearly so, acute, acuminate, or sometimes awn-pointed, carinate, usually scabrous on the keel and sometimes on the back; lemma obtuse, usually shorter and thinner in texture than the glumes, awnless or dorsally awned, often hairy on the callus; palea usually shorter than the lemma, 2-nerved in only a few species, usually small and nerveless or obsolete. Annual or usually perennial, delicate or moderately tall grasses, with glabrous culms, flat or sometimes involute, scabrous blades, and open or contracted panicles of small spikelets. Species about 100, in the temperate and cold regions of the world, especially in the Northern Hemisphere. About 25 species are found in the United States, some of these being found also in Europe. Type species : Agrostis stolonifera L. Agrostis L., Sp. PI. 61, 1753; Gen. PI., ed. 5, 30. 1754. Linnaeus describes 12 species, dividing them into two groups, Aristatae and Muticae. The descrip- tion of the genus refers to the lemma as being awned and to the presence of a palea ("Cor. bivalvis . . . altera majore aristata"). If the type species must agree with the description in the fifth edition of the Genera Plan- tarum, 1 it must be chosen from the first group, Aristatae, and from those 1 See American Code of Botanical Nomenclature, Bull. Torrey Club 84 : 174. 1907. The statement is made that "the genera of Linnseus's Species riantarum (1753) are to be typified through the citations given in his Genera Plantarum (1754)." There is no citation given for Agrostis and the code docs not definitely require that the genera must be interpreted by the descriptions here given ; hence the type species may be chosen inde- pendent of this description. 126 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. FIG. GG.Calamovilfa longifolia. Plant, X \ ; spikelet and floret, X 5. GENERA OF GRASSES OF THE UNITED STATES. 127 species possessing a palea. Prom this standpoint the type species would be Agrostis spica-venti, which is referred by many botanists to Apera but which is here included in Agrostis. However, the description of Agrostis in the fifth edition was not written by Linnauis for that edition. It was copied f:*om the first edition, published in 1737, at which time LinnaBUs's concept of Agrostis was chiefly based on Stipa calamagrostis. By the time the Species Plantarum was prepared his concept of the genus Agrostis had changed, but he did not make the corresponding change in the description in the fifth edition of the Genera Plantarum which he prepared at the same time. It seems best, then, to ignore this description and select the type species from the economic species. Therefore A. stolonifera * has been selected as the type species of Agrostis. Several of the original species are now referred to other genera: .1. miliacea and A. paradoxa to Oryzopsis; A. arundinacea to Oalamagrostis ; A. minima to Mibora ; A. virginica and A. indica to Sporobolus. Vilfa Adans., Fam. PI. 2: 495. 1763. Adanson cites " Gramen canin. supin. C. B. Theat. 12 " arid in the index, " Gramen canin. supin. minus C. B." Lin- naeus 2 gives under Agrostis stolonifera the citation, " Gramen cariinum supinum minus Scheuch. gram. 128." Scheuchzer 8 credits the citation to C. Bauhin. Therefore Agrostis stolonifera L. is the type of Vilfa Adans. Apera Adans.. Fam. PI. 2: 495. 1763. Adanson refers directly to "Agrostis 1. Lin. Sp. 61." The first species of Agrostis described by Linnaeus in his Species Plantarum (p. 61) is A. spica-venti, which becomes the type of Apera. Trichodium Michx., Fl. Bor. Amer. 1: 41, pi. 8. 1803. Two species are de- scribed, T. laxiflorum and T. decumbens. The first species, iliustiated in plate 8, is the type. This is the same as Afrostis hiemalis. Trichodium decumbens is the same as A. perennans. Michaux distinguished the genus from Agrostis by the absence of the palea. Agraulus Beauv., Ess. Agrost. 5, pi. 4, f. 7. 1812. Two species, based on Afjrostis canina L. and A. alpina Willd., are included, the first being figured and therefore the type. Anemagrostis Trin., Fund. Agrost. 128. 1820. Two species, based on Agrostis spica-venti L. and A. interrupta L., are included, the first of which is taken as the type. Notonema Raf., Neogenyt. 4. 1825. A single s-pecies is included, Agrostis arachnoides Ell. (A. elliottiana Schult.) Podagrostis Scribn. and Merr., Contr. U. S. Nat. Herb. 13 : 58. 1910. Based upon Agrostis, section Podagrostis Griseb. in Ledeb. Fl. Ross. 4: 436. 1853. A single species, Agrostis aequivalvis Trin., referred here in each case. A. thur- beriana Hitchc. also belongs to this group, which forms a section of Agrostis. In Agrostis spica-venti, A. aequivalvis,. and A. thurberlana the rachilla is prolonged behind the palea as a minute bristle or stipe, and the lemma and palea are nearly equal and about as long as the glumes. The palea is obsolete in many species (which have been separated by some authors under the generic name of Trichodium), and is much shorter than the lemma in several other species. The awn, when present, may arise from the back of the lemma just above 1 1 See Hitchcock, Bot. Gaz. 38:141. 1904. On the basis of the specimen in the Lin- naean Herbarium and of the synonymy, the name A. stolonifera was there applied to the species called A. vertictllata Vill. But on reconsideration it seems best to accept the name cis applied by Swedish botanists. Linnaeus was most familiar with the Swedish grass, and cites as the first synonym under A. stolonifera the phrase name he had applied to it in his Flora Suecica. He confused with this the South European species, A. ver- ticillata, a specimen of which in his herbarium he marked " A. stolonifcra/' but we may assume that he intended to apply the name A. stolonifera to the grass from Sweden. In the latter work Linnaeus states that the plant is known popularly as Kryp-hwen. Dr. Carl Lindman, who has kindly sent a series of specimens of the species in question, states in a letter that the grass in Sweden called Krypven (the modern spelling) is the species described by Swedish botanists as A. stolonifera. This has a long ligule, an open panicle, and an erect culm decumbent at base or producing stolons. 2 Sp. PI. 62. 1753. 3 Agrost. 128. 1719. 128 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. the base (A. howellli Scribn.) or from about the middle (A. exarata microphylla (Steud.) Hitchc.) or from just below the apex (A. spica- venti, A. ellio ttiana) . The hairs on the callus are usually minute, but are half as long as the lemma in A. hallii Vasey. Three of our species are annuals, A. spica-venti L., introduced from Europe; A. exigua Thurb., of California; and A. ellio ttiana Schult., of the Southern States. The genus furnishes several species that are important forage plants either under cultivation or in the mountain mead- ows of the Western States. The most important is Agrostis palustris Huds. (A. alba of authors 1 ) (PI. XIII; fig. 67), known usually as redtop because of the reddish 1 The name Agrostis alba L. (Sp. PI. G3. 1753) is of doubtful application. In the original publication the name is founded solely on the citation " Roy. lugdb. 59 " (Royen, Flora Ley- densis). Royen's citation of synonym refers to Poa (appar- ently P. nemoralis). There are several sheets in Linnaeus's herbarium, one of which bears the name, Agrostis alba, in Linnseus's script. These speci- mens are the Agrostis alba as generally understood, but, FIG- 07. Redtop, Agrostis falustris. Plant, X ; spikelet, open and closed, and floret, X 5. Bui. 772, U. S. Dept. of Agriculture. PLATE XIII. REDTOP (AGROSTIS PALUSTRIS). Bui. 772, U. S. Dept. of Agriculture. PLATE XIV. TIMOTHY (PHLEUM PRATENSE). GENERA OF GRASSES OF THE UNITED STATES. 129 color of the panicle. This species is an erect plant 2 to 4 feet high, producing rhizomes, and often decumbent at base, with flat blades, prominent, somewhat pointed ligule, and an opeia, usually red- dish panicle, 2 to 12 inches long, contracted in fruit, the branches in whorls. Redtop is cultivated as a meadow and pasture grass in the Northern States, especially upon soils lacking in lime and upon soils too wet for timothy. In Pennsylvania and some other localities this species is called herd's-grass. Agrostis capillaris L. (A. tennis Sibth., A. vulgaris With., A. alba vulgaris Thurb.), Rhode Island bent, 1 differs from red- top in its smaller size, more delicate culms and foliage, short truncate ligule, smaller, more open, and fewer flowered panicle, not contract- ing after flowering. Stolons are usually absent but may be as much as 4 to 8 inches long. Rhode Island bent is often used as a lawn grass, especially in the Northeastern States, where the soil is lacking in lime and bluegrass does not thrive. In some botanical works the name Agrostis canina has been incorrectly applied to Rhode Island bent. Agrostis canina L., a European species occasionally introduced into the Eastern States, is a frequent constituent of the commercial seed of creeping bent. It is called velvet bent and gives promise of being a fine lawn grass. Carpet bent, also called creeping bent, is a form of A. stolonifera. This produces stolons from 1 to 4 feet long and is also used as a lawn grass in the same region as that described for Rhode Island bent. The seed has been imported from southern Germany. Fiorin is a name that was applied in England to a coast form with stoloniferous habit, long ligule, and narrow dense panicles. This form is found along the northern Atlantic coast of Europe and America and along the Pacific coast from British Columbia to north- ern California. It has been called A. maritima Lam. and A. alba mcuritima (Lam.) Meyer. It is apparently indigenous in America, while A. capillaris and A. palmtris appear to be introductions. Several native species of Agrostis are found in the western part of the United States, especially in mountain meadows. One of the commonest of the western species is A. exarata Trin., with contracted, sometimes spikelike, panicles and awned or awnless spikelets, found at all altitudes throughout the western portion of the United States. according to Jackson (Index to the Linnsean Herbarium, Proc. Linn. Soc. London, 124th Sess. Suppl. 1912), these specimens were added to the herbarium after 1753 and can not, therefore, have weight in determining the original application of the name. Lin- naeus did not refer, under Agrostis alba, to his flora of Sweden. It would appear that he did not intend to apply the name originally to a Swedish plant. The species usually known as Agrostis alba- is common in Sweden, but apparently was included by Linnaeus under A. stolonifera, to which it is closely allied. It was not until later that he applied the name to the species as now represented in his herbarium. Under these circumstances it seems best to drop the name Agrostis alba, as has been done by Piper (U. S. Dept. Agr. Bull. 692, 1918) and by Stapf, as indicated in a letter to Piper. 1 See Piper, The Agricultural Species of Bent Grasses. U. S. Dept. Agr. Bull. 692. 1918 97709 19 Bull. 772 9 130 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. This is an important range grass. Common on the Pacific slope is A. diegoensis Vasey, with creeping rhizomes, spreading panicles, and often awned spikelets. Two native species belonging to the group in which the palea is lacking are common in -the eastern United States. Agrostis perennam (Walt.) Tuckerm. is a woodland species with open panicle. Agrostis hiemalis (Walt.) B. S. P. (fig. 68) is a delicate open-ground species with very diffuse capillary pani- cle, which at maturity breaks away from the plant as a tumble- weed. This species, called hair- grass and tickle grass, is found throughout the United States. Agrostis spica-venti L. (fig. 69), a European species, sparingly introduced in the Eastern States, has been made the type of a distinct genus, Apera, being distinguished by the prolongation of the rachilla and the long delicate awn from FIG. 68. Tickle grass, Agrostis hiemalis. Plant, X \ ', spikelet and floret, X 5. GENERA OF GRASSES OF THE UNITED STATES. 331 FIG. 69. Agrostis spica-venti. Plant, X I ; g^mes and floret, X 5. 132 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. just below the apex of the lemma. These characters are not deemed sufficient to separate it from our species. The rachilla is prolonged in A. aequivalvis and a similar awn is found in the annual A. elliot- tiana Schult. For a revision of the species of Agrostis found in the United States, see Hitchcock, U. S. Dept. Agr., Bur. PL Ind. Bull. 68. 1905. 57. PHIPPSIA (Trin.) 11. Br.' Spikelets 1-flowered, disarticulating above the glumes, the rachilla not prolonged; glumes unequal, minute, the first sometimes wanting; lemma thin, somewhat keeled, 3-nerved, acute; pa lea a little shorter than the lemma, dentate. A dwarf, tufted per- ennial, with n a r r o w, few - flowered panicles of small spikelets. Spe- cies one, in the arctic regions of both hemi- spheres; also on the al- pine summits of Colo- rado. FIG. 70. Phippsia algida. Plant, X ; spikelet and branchlet of inflorescence with the glumes of lower spikelets remaining, and floret, all X 5. Type species : Agrostis Soland. ( Nlpou<' forme, both referable to Ginna poaeformis (H. B. K.) Scribn. and Merr. The prolongation of the rachilla is less than 0.5 mm. in our species, but in Cinna poaeformis of Mexico it is half as long as the palea. The palea is 1-nerved in C. arundinacea. In C. poaeformis the 2 nerves are close together but distinct. In C . latifolia the palea is apparently 1-nerved, but the 2 nerves separated when the palea is split along the keel. 134 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. Cinna arundinacea (fig. 72), with somewhat contracted panicle and spikelets 5 mm. long, grows in moist, usually shaded places in the eastern United States; C. latifolia (Trev.) Griseb., with open panicle and spikelets 4 mm. long, grows in damp woods across the continent in the northern part of the United States, mostly at medium and high elevations. Both species furnish ex- cellent forage, but are usu- ally not abundant enough to be of much importance. 60. LIMNODEA L. H. Dewey. Spikelets 1-flowered, disarticulating below the glumes, the rachilla pro- longed behind the palea as a short, slender bristle; glumes equal, firm; lemma membranaceous. smooth, FIG. 72. Wood reed-grass, Cinna arundinacea. , '., _ . Plant, x i ; spikeiet and floret, x 5. nerveless, 2-tootned at the GENERA OF GRASSES OF THE UNITED STATES. 135 apex, bearing from between the teeth a slender bent awn, twisted at base ; palea a little shorter than the lemma. A slender annual with flat blades and narrow panicles. Species one, Florida to Texas. Type species : Greenia arkansana Nutt. Greenia Nutt., Trans. Amer. Phil. Soc. 5: 142, 1837, not Greenea Wight and Arn., 1834. Type O. arkansana, the only species described. Sclerachne Torr. ; Trin., Mem. Acad. St. PStersb. VI. Sci. Nat. 4 1 : 273, 1841, not Sclerachne R. Br. and Benn., 1838. Two species are described, S. arkansana Torr. and 8. pilosa Trin. The first, based on Greenia arkansana Nutt., is the type. Thurberia Benth., Journ. Linn. Soc. Bot. 19: 58, 1881, not Thurberia A. Gray, 1854. Type Greenia arkansana Nutt., the name Thurberia being substi- tuted for Greenia. Limnodea L. H. Dewey, Contr. U. S. Nat. Herb. 2: 518. 1894. Only one spe- cies described. Limnodea arkansana (Nutt.) L. H. Dewey (fig. 73), has probably no agricultural value. A form with pilose t FIG. 73. Limnodea arkansana. Plant, X I ; spikelet and floret, X 5. 136 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. glumes has been named L. arkansana pilosa (Trin.) Scribn. 61. ALOPECURUS L., the meadow foxtails. Spikelets 1 -flowered, disar- ticulating below the glumes, strongly compressed laterally; glumes equal, awnless, usually united at base, ciliate on the keel; lemma about as long as the glumes, 5-nerved, ob- tuse, the margins united at base, bearing from below the middle a slender dorsal awn, this included or ex- serted two or three times the length of the spikelet; palea wanting. Low or moderately tall per- ennial grasses with flat blades and soft, dense, spikelike pan- icles. Species about 25, in tem- perate regions of the North- FIG. 74. Meadow foxtail, Alopecurus pratensis. Plant, X I ; spikelet and floret, X 5. ern Hemisphere. Of the eight North American species, two are introductions from Europe and two are widely distributed in GENERA OF GRASSES OF THE UNITED STATES. 137 Eurasia. Some of the European species with a distinct palea have been segregated as the genus Colobachne. Type species: Alopecurus pratensis L. Alopecurus L., Sp. PI. 60, 1753; Gen. PL, ed. 5, 30. 1754. Four species are described, A. pratensis, A. geniculatus, A. hordciformis, and A. monspeliensis. The third and fourth species do not agree with Linnseus's generic description and are now referred, the third to Pennisetum and the fourth to Polypogon. The other two were well known to Linnaeus and were described in his flora of Sweden. The first, being an economic species, is chosen as the type species of the genus. Alopecurus pratensis L. (fig. 74), meadow foxtail, is sometimes used as a meadow grass in the eastern United States. It is recom mended for mixtures on moist soil, being nutritious and producing early forage. Meadow foxtail is an erect grass, 2 to 3 feet tall, with short rhizomes, loose, often inflated, sheaths, and spikes or heads 2 to 4 inches long and about one-fourth of an inch thick. Introduced from Europe, where it is favorably known as a meadow grass. Alopecurus geniculatus L. is a low, pale, soft grass, usually 6 to 18 inches high, with decumbent rooting bases and slender panicles 1 to 3 inches long and about one-eighth of an inch thick, the delicate awn bent and protruding about twice the length of the spikelet. Found in moist places across the continent. An allied and more common species, A. aristulatus Michx. (A. geniculatus aristulatus (Michx.) Torr.), is distinguished by the scarcely exserted awns. Alopecurus alpinus J. E. Smith (A. occidentalis Scribn.), a northern species extending into the Rocky Mountains of the United States, has a short, thick spike with spikelets woolly all over. Alopecurus cali- fornicus Vasey, of the northwestern Pacific coast region, has slender spikes, 1 to 3 inches long and one- fourth of an inch thick, the spike- lets 3 mm. long. The species of Alopecurus are all palatable and- nutritious, but usually are not found in sufficient abundance to be of great importance. 62. POLYPOGON Desf. Spikelets 1-flowered, the pedicel disarticulating a short distance below the glumes, leaving a short-pointed callus attached; glumes equal, entire or 2-lobed, awned from the tip or from between the lobes, the awn slender, straight ; lemma much shorter than the glumes, hyaline, usually bearing a slender straight awn shorter than the awns of the glumes. Annual or perennial usually decumbent grasses, with flat blades and dense, bristly, spikelike panicles. Species about 10, in the tem- perate regions of the world, chiefly in the Eastern Hemisphere, three species being introductions into the United States. Type species : Alopecurus monspeliensis L. Polypogon Desf., Fl. Atlant. 1: 66. 1798. Only one species described, this based on Alopecurus monspeliensis L. 138 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. Polypogon lutosus (Poir.) Hitchc. (Agrostis lutosa Poir., P. lit tordlis J. E. Smith, based on Agrostis littoralis With., 1796, not Lam. 1791), a perennial with awns scarcely longer than the glumes, is frequent on the Pacific coast. Polypogon monspeli- ensis (L.) Desf. (fig. 75) is an annual with soft, bristly, green or yellowish spikes 1 to 6 inches long, the awns much longer than the glumes. This is a common weed on the Pacific coast and is occa- sional in the Atlantic \ FIG. 75. Polypogon monspeliensis. Plant, X I ; spikelet and floret, X 5. States. Polypogon maritimus "Willd. is a rare species found in Georgia and California, and differs from the preceding in having deeply lobed lemmas, the lobes ciliate. Our species are relished by GENEKA OF GRASSES OF THE UNITED STATES. 139 stock, and P. monspeliemis is sometimes sufficiently abundant on low meadows to be of importance. 63. LYCURUS H. B. K. Spikelets 1-flowered, the rachilla articulate above the glumes; glumes awned, the -first usually 2-awned; lemma narrow, firm, longer than the glumes, terminating in a slender awn. Low perennial grasses, with dense spikelike panicles, the spikelets borne in pairs, the lower of the pair sterile, the short branchlets deciduous. Spe- cies two, in arid regions from the southwestern United States to north- ern South America. Type species : Lycurus phleoides H. B. K. Lycurus H. B. K., Nov. Gen. and Sp. 1: 141, pi. 45. 1816. Two species are described, L. phleoides and L. phalaroides. The first species, being figured, is chosen as the type. Pleopogon Nutt, Journ. .Acad. Nat. Sci. Phila. II. 1: 189. 1848. A single species, P. setosum, is included. This is Lycurus phleoides. Lycuvus phleoides (fig. 76), the only species in the United States, is a low bunch-grass with slender erect culms about a foot high, with a dense, narrow, lead-color panicle 1 or 2 inches long. The species, sometimes called Texas timothy and wolftail, is common on the Mexican Plateau and FIG. 76. Wolftail, Lycurus phleoides. Plant, X 2 ; group of two spikelets, glumes of fertile spikelet, and two views of fertile floret, X 5. extends north to Texas, Colorado, and Arizona. It is often an im- portant constituent of grazing areas. 140 BULLETIN 772, IT. S. DEPARTMENT OF AGRICULTURE. 64. PHLEUM L. Spikelets 1-flowered, laterally compressed, disarticulating above the glumes ; glumes equal, membranaceous, keeled, abruptly mucronate or awned ; lemma shorter than the glumes, hyaline, broadly truncate, 3 to 5 nerved; palea narrow, nearly as long as the lemma. Annuals or perennials, with erect culms, flat blades, and dense, cylin- dric panicles. About 10 species, in the temperate regions of both hemi- spheres. Type species : Phleum pra- tense L. Phleum L., Sp. PI. 59, 1753 ; Gen. PI., ed. 5, 29. 1754. Four species are described, P. pratense, P. alpinum, P. arenarium, and P. schoe- noides. The first species is chosen as the type because it is the only cultivated spe- cies in the genus. The first three species are still re- tained in Phleum ; the fourth is referred to Heleochloa. Stelephuras Adans., Fam. PI. 2: 31. 607. 1763. Based on Phleum L. Four species of Phleum are found in the United States. Our only native species is P. alpinum L., mountain timothy, a per- ennial with short spikes, two or three times as long as wide, found in the northern regions of Eurasia and America and extending south in the mountains of Xew Eng- land, in the Rocky Moun- tains to Mexico, and in the Sierra Nevada and Coast Ranges to the San FIG. 77. Timothy, Phleum pratense. Plant, X i I T . ,.- . spikelet and floret, X 5. JaCintO Mountains. GENERA OF GRASSES OF THE UNITED STATES. 141 Mountain timothy produces a fair amount of nutritious forage, which remains green till late in the season and is considered a valu- able late sheep feed. It is an important constituent of mountain meadows. This species is distinguished from common timothy by the shorter, broader heads and by the absence of the swollen base of the stem or so-called bulb. Two species, P. graecum Boiss. and Heldr. and P. bellardi Willd., are annuals introduced from Europe and found here only at a few coast points on dumping grounds for ballast. The fourth species is timothy, PHlewn pratense L. (PL XIV; fig. 77), an erect, short-lived perennial, 2 to 4 feet tall, with elongate cylindric inflorescences or " heads " several times longer than broad. The stems are swollen at the base, and the glumes, like those of moun- tain timothy, are ciliate on the keel. Timothy, a native of Europe and northern Asia, is now commonly cultivated in this country and in Europe as a meadow grass, and is found growing without culti- vation in waste places, roadsides, and old fields throughout most of the United States. It is the most important meadow grass grown in America, and timothy hay is the standard for all grass hay sold on the market. The region of the United States favorable for the grow- ing of timothy is the crop area known as the cool humid region, which includes the northeastern portion west to the Great Plains and south to Virginia and Missouri, or farther in the mountains. Another timothy area is found on the Pacific coast from northern California to Puget Sound. Much timothy is grown in favorable localities in the western mountains. In some localities timothy is known as herd's- grass. See Evans, U. S. Dept. Agr., Farmers' Bull. 502, 1912; McClure, U. S. Dept. Agr., Farmers' Bull. 508, 1912; Williams, U. S. Dept. Agr. Yearbook, 1896: 147, 1897; Scribner, U. S. Dept. Agr., Div. Agrost. Bull. 20: fig. 47. 1900. 65. GASTRIDIUM Beauv. Spikelets 1-flowered, the rachilla disarticulating above the glumes, prolonged behind the palea as a minute bristle ; glumes unequal, some- what enlarged or swollen at the base ; lemma much shorter than the glumes, hyaline, broad, truncate, awned or awnless; palea about as long as the lemma. Annual grasses, with flat blades and pale, shining, spikelike pan- icles. Species two, in the Mediterranean region ; one introduced into the United States. Type species : M ilium lendigerum L. Gastridium Beauv., Ess. Agrost. 21, pi. 6, f. 6. 1812. Beauvois mentions only one species, Milium lendigerum, but the description of the plate bears the name Gastridium australe. 142 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. Gastridium ventricosum (Gouan) Schinz and Thell. 1 (G. lendi- gerum (L.) Gaud.) (fig. 78), with an awned lemma, a common weed on the Pacific coast, appears to have no economic value. 66. LAGUBUS L. Spikelets 1-flowered, the rachilla disarticulating above the glumes, pilose under the floret, produced beyond the palea as a bristle; glumes equal, thin, 1-nerved, villous, gradually tapering into a plumose aristiform point; lemma shorter than the glumes, thin, glabrous, bear- ing on the back above the middle a slender, exserted, somewhat geniculate, dorsal awn, the summit bifid, the divisions delicately awn- tipped; palea narrow, thin, the two keels ending in minute awns. An annual grass, with pale, dense, ovoid or oblong woolly heads. Species one, in the Mediterranean region and in- troduced sparingly in Cali- fornia. Type species : Lagurus ovatus L. Lagurus L., Sp. PL 81, 1753; Gen. PI., ed. 5, 34. 1754. Only one species described. Lagurus ovatus (fig. 79) is sometimes cultivated as an ornamental, the woolly heads being used for dry bouquets. 67. EPICAMPES Presl. Spikelets 1-flowered, the rachilla disarticulating above 1 This name is based on Agrostis ventricosa Gouan, Hort. Monsp. 39, pi. 1, f. 2, 1762, which was published earlier in the year than Milium lendi- gcrum L., Sp. PI., ed. 2, 91, 1762, as shown by Linnaeus's reference to Gouan's work in the preface to the sec- ond edition of his Species Plantarum. FIG. 78. Gastridium vcntricosum. Plant, X spikelet and floret, X 5. GENERA OF GRASSES OF THE UNITED STATES. 143 the glumes; glumes about equal; lemma equaling or longer than the glumes, 3-nerved, often bearing a slender awn just below the tip. FIG. 79. Hare's-tail grass, Lagurus ovatus. Plant, X I ; spikelet and floret, X 5. Tall cespitose perennials, with open, narrow, or spikelike panicles. Species 15, northern South America to Mexico, 5 extending into the southwestern United States. 144 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. Type species : Epicampes strictus Presl. Epicampes Presl, Rel. Haenk. 1: 235, pi. 39. 1830. Only one species de- scribed. Crypsinna Fourn., Mex. PI. 2: 90. 1SS6. Three species are mentioned, C. stricta, C. macroura, and C. setifolia. In the generic description the panicle is said to be densely spiciform. This applies best to the second spe- cies, C. macroura, which is chosen as the type. One species, Epi- campes rigens Benth. (fig. 80), with long, slender, cylindric, pale, spikelike pan- icles, the glumes shorter than the lemma, is found from western Texas to southern California. This species, called deer-grass, and the four other species, E. ligulata Scribn., E. berlandieri Fourn., E. subpatens Hitchc., 1 and E. emersleyi 1 Epicampes subpatens, n. sp. Culms erect, glabrous, 50 to 100 cm. tall ; sheaths glabrous, slightly scabrous, compressed-keeled, especially those of the innovations ; ligule softly membranace- ous, 1 to 2 cm. long ; blades flat or folded, scabrous, 1 to 3 mm. wide, the lower as much as 50 cm. long ; panicles narrow but rather loose, mostly 20 to 40 cm. long, the branches ascend- ing, more or less fascicled or whorled, naked below ; spikelets about 3 mm. long, FIG. 80. Deer-grass, Epicampes ricfcns. Plant, X I ; spikelet and floret, X 5. GENERA OF GRASSES OF THE UNITED STATES. 145 (Vasey) Hitchc. (Muhlenbergia emersleyi Yasey, M. vaseyana Scribn.) , are forage grasses. A Mexican species, E. macrowa Benth., is of considerable economic importance, the roots being used in the manufacture of scrubbing brushes. 68. MUHLENBEBGIA Schreb. Spikelets 1-flowered, the rachilla disarticulating above the glumes; glumes usually shorter than the lemma, obtuse to acuminate or awned, the first sometimes small or rarely obsolete; lemma firm- membranaceous, 3 to 5 nerved, with a very short, usually minutely pilose callus, the apex acute, sometimes bidentate, extending into a straight or flexuous awn, or sometimes only mucronate. Perennial or rarely annual low or moderately tall grasses, tufted or rhizomatous, the culms simple or much branched, the in- florescence a narrow or open panicle. Species about 80, mostly in Mexico and the southwestern United States, a few in the eastern part of the Old World ; 40 species in the United States. Type species: Muhlenbergia schreberi Gmel. Muhlenbergia Gmel., Syst. Nat. 2 : 171. 1791. Only one species mentioned. Dilepyrum Michx., Fl. Bar. Amer. 1 : 40. 1803. ' Two species are described, D. urixtomun, which is Brachyelytrum erectum, and D. minutiflorum, which is MuMenbergfa schreberi Gmel. They are equally eligible as the type. The second is chosen, in order to conserve the generic name Brachyelytrum. Podosemum Desv., Nouv. Bull. Soc. Philom. Paris 2 : 188. 1810. The type is Stipa capillaris Lam. (P. capillaris Desv.), the only species mentioned. Olomena Beauv., Ess. Agrost. 28, pi. 7, f. 10. 1812. The type is C. peruviana, the only species mentioned. This is Muhlenbergia peruviana (Beauv.) Steud. Trichochloa Beauv., Ess. Agrost. 29, pi. 8, f. 2. 1812. The type and only species is T. purpurea. This has not been identified. Roemer and Schultes say it is Trichochloa expansa DC. (Muhlenbergia expanse (DC.) Trin.). Tosagris Beauv., Ess. Agrost. 29, pi. 8, f. 3. 1812. The type is T. agrostidea, the only species mentioned. This has not been identified, but it appears to be a species of Muhlenbergia. Sericrostis Raf., Neogenyt. 4. 1825. "Type Stipa sericea MX. or diffusa Walter." This is Muhlenbergia capillaris (Lam.) Trin. Calycodon Nutt, Journ. Acad. Phila. II. 1: 186. 1848. The type is C. mon- tanum (Muhlenbergia montana Hitchc.), the only species described. Vaseya .Thurb., in Gray, Proc. Acad. Phila. 1863 : 79. 1863. The type is V. comata Thurb., the only species described. This is Muhlenbergia andina (Nutt.) Hitchc. (Calamag'rostis andina Nutt). often tinged with purple ; glumes about as long as the lemma, papery, acutish, scabrous ; lemma narrowed and scabrous abovo, villous below, awnless, or occasionally those of a few of the spikelets with a flexuous awn about 1 cm. long. Type, U. S. National Herbarium no. 905799, collected in a rocky ravine, Guadeloupe Mountains, near Queen, N. Mex., altitude 7,000 feet, Sept. 5, 1915, by A. S. Hitchcock, no. 13541. This species is closely allied to Epicampes emersleyi, from which it differs in the awn- less spikelets and larger, looser, and more spreading panicles. The writer examined the two forms in the Guadeloupe Mountains, southern New Mexico, and concluded from these field observations that the awned and awnless forms represented two distinct but closely allied species. The delicate awns are not noticeable at a distance but the more open panicle was always found to be associated with the awnless spikelets. Other specimens in the U. S. National Herbarium. TEXAS : Limpia Canyon, Nealley 133. Chisas Mountains, Bailey 392. Guadeloupe Mountains, Bailey 739. Western Texas, Wright 729. NEW MEXICO : Socorro, Plank 53. Silver City, Greene 439. ARIZONA : Patagonia, Hitchcock 3719. Chiracahua Mountains, Tourney 15a. Santa Catalina Moun- tains, Griffiths 7149. 1 Syst. Veg. 2 : 384. 1817. 97769 19 Bull. 772 10 146 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. Chaboissnea Fourn., Mex. PI. 2: 112. 1886. A single species, C. ligulata, is included. This is Muhlenbergia ligulata (Fourn.) Scribn. and Merr. Muhlenbergia is a somewhat artificial genus, including species of very diverse habit. It differs from Sporobolus in the 3-nerved awned or mucronate lemma, and from Agrostis in the firmer lemma, usually longer than the glumes. One group, including M. squarrosa (Trin.) Rydb. (fig. 81), M. repens (Presl) Hitchc., and their allies, has been usually referred to Sporobolus. The species of this group are in- cluded in Muhlenbergia because of the 3-nerved mucronate or awned lemmas, but they form a distinct section or possibly a distinct genus. FIG. 81. Muhlenbergia, squarrosa. Plant, X \ ; spikelet and floret, X 5. In M. repens the lateral nerves of the lemma are commonly obsolete, and the apex is sometimes scarcely mucronate. Of the species found in the United States two are annuals, M. de- pauperata Scribn., with acuminate or awned glumes, and M. micro- sperma (DC.) Kunth, with obtuse glumes, both growing in the ex- treme Southwest. The latter species produces cleistogenes in the axils of the lower sheaths. Muhleiibergia mexicana (L.) Trin. and its allies have branching stems and numerous panicles. The glumes are GENERA OF GRASSES OF THE UNITED STATES. 147 reduced in M. schreberi (fig. 82), the type species, the first being obsolete and the second not over 0.5 mm. long. In M. montana (Nutt.) Hitchc. (Calycodon montanum Nutt ; Muhleribergia trifida Hack. ; M. gradlis of authors, not H. B.K.) the sec- ond glume is 3- toothed. Muhlen- bergia capillaris (Lam.) Trin. (fig. 83), of the South- ern States, is a handsome peren- nial with diffuse purple panicles. There are nine species in the Eastern States; the others are western or mainly southwestern. Many of the west- ern species are important range grasses and often form a consider- able proportion of the grass flora of the arid and semi- arid regions. The commonest of these are M. mon- tana and M. wrightii V a s e y. The second has a spikelike leaden- hued panicle. FIG. 82. Nimble Will, Muhlenbergia schreberi. Plant, X I ; branchlet showing both first ana second glumes of two spikelets, spikelet with obsolete first glume, and floret, all X 5. 148 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. FIG. 83. Muhlenbergia capillaris. Plant, X I ; spikelet, X 5. GENERA OF GRASSES OF THE UNITED STATES. 149 69. SPOROBOLUS R. Br. Spikelets 1-flowered, the rachilla disarticulating above the glumes; glumes awnless, usually unequal, the second often as long as the spike- let; lemma membranaceous, 1-nerved, awnless; palea usually prominent and as long as the lemma or longer; seed free from the pericarp. Annual or perennial grasses, with small spikelets in open or contracted PIG. 84. Smut-grass, Sporobolus berteroanus. Plant, X i ; spikelet and floret, X 5. 150 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. panicles. Species about 95, in the warm regions of both hemispheres, most abundant in America ; 36 species in the United States. Type species : Agrostis indica L. Sporobolus R. Br., Proclr. Fl. Nov. Holl. 169. 1810. Three species are de- scribed, & indicus, 8. elongatus, and 8. pulchellus. Brown states that Sporobo- lus includes Agrostis species of Linnaeus. Of the three species described by Brown only the first was known to Linnaeus and included by him under Agrostis. Hence the first species is chosen as the type. Agrosticula Raddi, Agrost. Bras. 33, pi. 1, f. 2. 1823. Type A. muralis, the only species described. Bennetia Raf., Bull. Bot. Seringe 1: 220. 1830. Afirostis jmicea Michx. is the only species included. This is Sporobolus gracilis (Trin.) Merr. Crystostachys Stend.. Syn. PI. Glum. 1: 181. 1854. The type is C. rapinata. the only species described. From the description this appears to be Sporobolus vaginaeflorus. Bauchea Fourn.. Mex. PI. 2: 87. 1886. Type B. karwinskyi, the only species described. This is Sporobolus u:rightii. The fruit is free from the lemma and palea, and falls readily from the spikelet at maturity. Because of this character the species have been called drop-seed grasses. The genus differs from Muhlenbergia in having 1 -nerved awnless lemmas and from Agrostis in having lemmas as long as the glumes or longer and as firm. Four species of the United States are annual. One of them, Sporobolus vaginae-flams (Torr.) Wood, is called poverty grass, because it grows in sterile soil. This has narrow panicles, partly or wholl}' inclosed in the sheaths. Several of the perennial species have creeping rhizomes. One of these, S. virginicus (L.) Kunth, is a common seashore grass in the Southern States. It has erect stems 6 to 10 inches tall, with spikelike panicles of pale spikelets. The other species of the genus are erect bunch-grasses. Sporobolus ~ber- teroanus (Trin.) Hitchc. and Chase (fig. 84), with long, slender, spikelike panicles, is common in the Southern States (S. indicus of the manuals, not S. indicus (L.) R. Br.). This species is called smut-grass, because the inflorescence is frequently affected with a black fungus. The glumes are about equal and much shorter than the lemma. Sporobolus wyptandrus (Torr.) Gray (fig. 85) is common on sandy soil, especially in the interior of the country. This has very small spikelets in panicles sometimes partly inclosed in the upper sheath, only the upper portion spreading, or even entirely inclosed in the swollen sheaths. There is a conspicuous tuft of hairs at the summit of the sheaths. In winter the leaves and stems become fibrous and much frayed out by the wind. Two species of the Southwest are important forage grasses in the arid and semiarid regions. Sporobolus cdroides Torr. (fig. 86), growing in dense, tough clumps, the stems 1 or 2 feet high, and with large spreading panicles, is found on somewhat alkaline soil and is called bunch-grass or alkali saccaton. It ranges from Nebraska to GENERA OF GRASSES OF THE UNITED STATES. 151 Montana and Texas. Sporobolus wrigJitii Munro, saccaton , is much taller, with a large but narrow panicle. This is found from Arizona to western Texas. Most of the per- ennial species of Sporobolus are pal- atable forage, grasses, but few 7 of them are abundant enough to be of im- portance. On the Arizona Plateau, S. interruptus Vasey is an important range grass. It is called black sporo- bolus, because of the dark, narrow, loosely flowered panicle. 70, BLEPHARONETJKON Nash. Spikelets 1 -flow- ered, the rachilla disarticu lating* above the glumes; glumes subequal, rather broad; lemma 3-nerved, the nerves densely pilose ; palea densely pilose be- tween the two nerves. A perennial grass with an open, nar- row panicle. Spe- cies one ; southwest- ern United States and northern Mex- ico. Type species: Vilfa tricholcpis Torr. Blepharo neuron Nash, Bull. Torrey Club 25: 88. 1898. Only one species men- tioned, B tricholepiS FIG. 85. Saud dropseed, Nporo&oZus cryptandrus. Plant, (Tor.) Nash. X i; spikelet and floret, the palea splitting, X 5. 152 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. FIG. 86 Alkali saccaton, Sporobolus air&ides. Plant, X I ; spikelet and floret, X 5. GENERA OP GRASSES OF THE UNITED STATES. 153 The single species (fig. 87) is a tufted grass about a foot high, found on open or rocky soil at middle altitudes from Colorado to central Mexico. It is a palatable grass, sufficiently abundant in places to be of importance. Until recent years the species was included in Sporobolus. 71. CKYPSIS Ait. Spikelets 1 -flowered, the rachilla disarticulating below the glumes; glumes about equal, narrow, acute; lemma broad, thin, awnless; palea similar to the lemma, about as long, 2-nerved, readily splitting between the nerves; fruit a utricle, the seed free from the thin pericarp. A spreading annual, with capitate inflorescences in the axils of broad bracts, these being enlarged sheaths with short rigid blades. Species one, in the Mediterranean region; sparingly introduced into the United States. Type species: Schoenus aculeatus L. Crypsis Ait., Hort. Kew. 1: 48. 1789. A single species is mentioned, with two varieties or forms, a (the equivalent of the species), based on Schoenus aculeatus L., and j3, based on Phlewm schoenoides L. The first is the type. Bentham and Hooker 1 state that the spikelet has four glumes and no palea. Hackel 2 states that the palea is 1-nerved. Our specimens show an evi- dently 2-nerved palea. FIG. 87. Blepharoneuron tricholepis. riant, X I ; spike- let and floret, X 5. 'Gen. PI. 8: 1139. 1883. 2 Engl. and Prantl, Pflanzenfam. 2 2 : 48. 1887 J _ 154 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. Crypsie acufoafa. (L.) Ait. (fig. 88) has been introduced in a few places in California. 72. HELEOCHLOA Host. Spikelets 1 -flowered, the rachilla disarticulating above the glumes; glumes about equal, narrow, acute; lemma broader, thin, a little longer than the glumes ; palea nearly as long as the lemma, 2-nerved, readily splitting between the nerves ; caryopsis free from the lemma and palea. Low perennial spreading grasses, with oblong, dense, spikelike panicles, terminal and on short lateral branches, the subtending leaves FIG. 88. Crypsis aculeata. Plant, X I ; spikelct and floret, the palea splitting, X 5. with inflated sheaths and reduced blades. Species about seven, in the Mediterranean region, one introduced into the United States. Type species : Heleochloa alopecuroides Host. Heleochloa Host, Gram. Austr. 1: 23. 1801. Two species are described, H. alopecuroicles and H. schoenoidcx, both of which are figured. The first is chosen as the type. Heleochloa schoenoides (L.) Host (fig. 89) has been introduced into the eastern United States at several points from Massachusetts and Delaware to Illinois. 73. BBACHYEJLYTBUM Beauv. Spikelets 1 -flowered, the rachilla disarticulating above the glumes, prolonged behind the palea as a slender naked bristle; glumes very short, unequal, the first sometimes obsolete, the second sometimes awned ; lemma firm, narrow, 5-nerved, the base extending into a pro- GENERA OF GRASSES OF THE UNITED STATES. 155 nounced oblique callus, the apex terminating in a long straight scabrous awn. Perennial erect, slender grasses, with short knotty rhizomes, flat blades and narrow, rather few-flowered panicles. Species one, North American. \ FIG. 89. Heleochloa schoenoides. Plant, X I ', spikelet and floret, the palea splitting, X 5. Type species: Muhlenbergia erecta Schreb. I.nichyelytrum Beauv., Ess. Ajri-ost. .">!>. pi. 9, f. 2. 1812. The type is the figured species, B. erectum, based 011 Huhlenberyia erecta. 156 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. Brachyelytrum erectum (Schreb.) Beauv. (fig. 90), found in rich rocky woods in the northeastern quarter of the United States, is of no economic importance. It has been known also as B. aristatum Beauv. 74. MILIUM L. Spikelets 1-flowered, disarticulating above the glumes; glumes equal, obtuse, membranaceous, rounded on the back; lemma a little shorter than the glumes, obtuse, awnless, obscurely nerved, rounded on the back, dorsally compressed, in fruit becoming indurate, smooth, and shining, the margins inclosing the lemma, as in Panicum. Moderately tall grasses with flat blades and open panicloe. Spe- cies about six, in- the cooler parts of Eurasia, one of which is found also in northeastern North America. Type species: Milium effusum L. Milium L., Sp. PI. 61, 1753; Gen. PI., ed. 5, 30. 1754. Two species are de- scribed, M. effusum and M. confertum. The first species is chosen as the type as it was the one best known to Linnaeus, being described in his flora of Sweden. The second species is now reduced to a variety of M. effusum. Milium is an ancient Latin name for the common millet of Europe (Panicum miliaceum L. ). Linnaeus applied this name to the genus above described. 1 Milium effusum L. (fig. 91) , millet grass, the only representative of the genus in America, is a slender erect perennial 3 to 4 feet tall, found in cool woods from Nova Scotia to Illinois. It is of no economic importance. 75. ORYZOPSIS Michx. Spikelets 1-flowered, disarticulating above the glumes; glumes about equal, obtuse or acuminate; lemma indurate, usually about as long as the glumes, broad, oval or oblong, nearly terete, usually pubescent, with a short, blunt, oblique callus, and a short, deciduous, sometimes bent and twisted awn ; palea inclosed by the edges of the lemma. Perennial, mostly low grasses, with flat or often involute blades and terminal narrow or open panicles. Species about 20, in the north temperate regions of both hemispheres; 13 species in the United States. Type species: Oryzopsis asperifolia Michx. (fig. 92). Oryzopsis Michx., Fl. Bor. Amer. 1 : 51. 1803. A single species described. Dilepyrum Raf., Med. Repos. 5: 351. 1808. Rafinesque here announces a new work and gives the names of several proposed new genera and species. One of these is "Dilepyrum, the Orizopsis of do [Michaux]." The type, then, is Ory- zopsis asperifolia Michx. Piptatherum Beauv., Ess. Agrost. 17. pi. 5, f. 10. 1812. Beauvpis mentions five species and figures two, P. coerulescens and P. punctatum. Milium coerules- cens, the basis of the first species, is chosen as the type. Eriocoma Nutt., Gen. PI. 1: 40. 1818. The type is E. cuspidata Nutt., the only species described. This is the same as Oryzopsis liymenoides. 1 For a discussion of Milium and Panicum, see Hitchcock and Chase, Contr. U. S. Nat. Herb. 15: 11. 1910. GENERA OF GRASSES OF THE UNITED STATES. 157 FIG. 90. Brachyelytrum erectum. Plant, X 1 ; branchlet, with glumes of two spikelets, and floret, X 5. 158 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. Urachne Trin., Fund. Agrost. 109. 1820. Trinius cites Beauvois's two figures mentioned above, which represent Piptatherum coerulescens and P. punctatum, and at the end of his generic description lists three species, U. coerulescens (M ilium coerulescens Desf.), U. rircscens (Milium paradoxum Scop.), and U. parviflora (Agrostis miliacca L.). The first of these is chosen as the type. Fendlera Steud., Syn. PI. Glum. 1 : 419. 1854. Type, F. rhynclielytroides Steud., the only species described. This is the same as Ory- zopsis hymenoides. The commonest species is Oryzopsis hymenoides (Roem. and Schult.) Kicker, found throughout the region west of the Rocky Mountains on dry soil. This has an open divaricate pani- cle and densely long-silky lemmas. The species of Oryzopsis are grazed by stock, but usually are not in suffi- cient abundance to be of impor- tance, except Indian mountain rice (O. hynwnoides) . The allied Mexican and South American genera, Nasella Desv. and Piptochaetium Presl, differ in having an obliquely obovate fer- tile lemma, the apex gibbous, and the awn eccentrically attached. 76. STIPA L., the spear-grasses. Spikelets 1-flowered, disarticu- lating above the glumes, the artic- ulation oblique, leaving a .bearded, sharp-pointed callus attached to the base of the floret ; glumes mem- branaceous, often papery, acute, FIG. 91. Millet grass, Milium effusum. Plant, X \ ', spikelet and floret, X 5. acuminate or even aristate, usually long and narrow ; lemma narrow, terete, firm or indurate, strongly convolute, terminating in a usually bent and twisted, prominent, persistent awn; palea inclosed in the convolute lemma. GENERA OF GRASSES OF THE UNITED STATES. 159 Perennial grasses, with usually convolute blades and narrow pan- icles. Species about 100, in the temperate regions of the world, especially on plains and steppes; 30 species in the United States, mostly in the western part. Type species : Stipa pennata L. Stipa L., Sp. 1M. 78, 1753 ; Gen. PI., ed. 5, 34. 1754. Limireus describes three species, . pennata, 8. juncea, and S. avenacca. The first two are from central and southern Europe, the third from Virginia. The first species is selected as the type. 160 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. Podopogon Raf., Neogenyt. 4. 1825. Two names are given, " Stipa avenacea L. and " barbatu " Michx., both belonging to the same species. Fie. 93. Porcupine grass, Stipa spartea. Plant, X 1 ; glumes and floret, X 2. GENERA OF GRASSES OF THE UNITED STATES. 161 Some of the western species have plumose or feathery awns, those of Stipa neo-mexicana (Thurb.) Scribn. being 4 to 8 inches long, plumose to the second bend, those of the handsome S. speciosa Trin. and Kupr. plumose below the single bend. A striking species of the upper Mississippi Valley is Stipa spartea Trin. (fig. 93), called porcupine grass and devil's darning needles. The rigid indurate fruiting lemma is about three-fourths of an inch long, tapering be- low into a very sharp hairy point, which acts like a barb, and termi- nating above in a stout awn as much as 6 inches long. At maturity the awn bends twice near the middle and becomes tightly twisted be- low the first bend. Variations in moisture cause the awn to twist and untwist, by which movement and by the aid of the sharp callus it can penetrate the soil. Several other species have elongate awns, such as S. avenacea L. of the eastern half of the United States and S. comata Trin. and Rupr. of the western half, the latter species being called needle-and-thread grass, because of the long flexuous upper portion of the awns. /Stipa viridula Trin. and its allies have a nar- row compact panicle and comparatively inconspicuous awns 1 or 2 inches long. One of these species, S. vaseyi Scribn., is called sleepy grass, because of the narcotic effects sometimes produced upon horses when they have fed upon it. Sleepy grass, found in New Mexico and Colorado, is a stout grass 3 to 5 feet high, with a narrow panicle as much as a foot long, the sheaths hairy at the throat. In S. tenuis- sima Trin. (fig. 94) of New Mexico the fruit is very small, less than 3 mm. long. The species of Stipa are for the most part valuable forage plants. The most important species on the ranges are S. viridula, S. minor (Vasey) Scribn., and & lettermani Vasey. They are known as porcu- pine grasses. All have narrow panicles. One of the Old World species, S. tenacissima L., furnishes a part of the esparto or alfa grass of Spain and Algeria that is used in the manufacture of paper and cordage. 77. AEISTIDA L., the needle grasses. Spikelets 1 -flowered, the rachilla disarticulating obliquely above the glumes; glumes equal or unequal, narrow, acute, acuminate, or awn-tipped ; lemma indurate, narrow, terete, convolute, with a hard, sharp-pointed, usually minutely bearded callus at base, terminating above in a usually trifid awn. Annual or perennial, mostly low grasses, with narrow, frequently convolute blades and narrow or sometimes open panicles. Species about 150, in the warmer regions of the world; 36 species in the United States ; especially abundant in the Southwestern States, 97769 19 Bull. 772 11 162 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. FIG. 94. Stipa tenuissima. Plant, X I ; spikelet, X 2 ; glumes and floret, X 5. GENERA OF GRASSES OF THE UNITED STATES. 163 Type species : Aristida adscensionis L. Aristida L., Sp. PI. 82, 1753; Gen. PI., ed. 5, 35. 1754. A single species is described. Streptachne R. Br., Prodr. Fl. Nov. Holl. 174. 1810. A single species, 8. stipoides, is included. In this the lateral awns are obsolete. Chaetaria Beauv., Ess. Agrost. 30, pi. 8, f. 5, 6. 1812. Twenty-five species are listed, two, C. stricta (based on Ari-stida stricta Michx.) and C. capillaris, are illustrated. Aristida stricta (fig. 5) is taken as the type. Curtopogon Beauv., Ess. Agrost. 32, 159, pi. 8, f. 7. 1812. The only species included is based on Aristida dichotoma L. Trixostis Rat, Bull. Bot. Seringe 1: 221. 1830. A single species, "Aristida, gracilis" [Ell.], is included. Moulinsia Raf., Bull. Bot. Seringe 1: 221. 1830. A single species, "Aristida lanosa " Muhl., is included. Ortachne Nees, in Seeman, Bot. Voy. Herald 225. 1857. A single species, based on Streptachne pilosa H. B. K., is included. In one group of the genus the lateral awns are reduced to mere points or are entirely absent. Two species of this group (section Streptachne) are found in Arizona, Aristida scabra (H. B. K.) Kunth, with a curved but not twisted awn, and A. schiedeanaTr'm. andRupr., with a twisted awn. The former is found also in southern Florida. In three species the awn is articulate at base, A. desmantha Trin. and Rupr., with short neck, A. tuberculosa Nutt., an annual with a slender, twisted neck, and A. calif omica Thurb., a perennial with a slender, twisted neck. Aristida dichotoma Michx., a small annual with a coiled central awn, is common in the Eastern States. Two other annuals are common in the eastern part of our country, A. gra- cilis Ell., with the central spreading or reflexed awn less than half an inch long, and A. oligantha Michx. (fig. 95), with awns 2 or 3 inches long. The type species, A. adscensionis L. (A. bromoides H. B. K.), has a wide distribution in warm countries and extends into the southwestern United States. This is a low annual, usually much branched at base, with contracted panicle, the first glume about half as long as the second, and awns about one-third of an inch long. A common perennial species in the semiarid regions of the West is A. longiseta Steud., called dog-town grass, because it is especially abundant on the new soil of prairie-dog communities. Aristida fend- leriana Steud. is an allied species of the same region. The first has a long second glume, about four-fifths of an inch long, and awns as much as 3 or 4 inches long. The second has a shorter second glume, about three-fifths of an inch long, and awns less than 2 inches long, and grows in dense tufts with curly leaves crowded at the base of the plant. Aristida purpurea Nutt. differs in having slender curved pedicels. These species are troublesome when the fruit is ripe, be- cause this with its spreading awns becomes detached at maturity and is blown about by the wind. These fruits are sometimes scattered in vast quantities, the wind hurling them across the plains with the sharp-pointed callus in advance. They work their way into the wool of sheep and into the nostrils and eyes of all classes of stock. 164 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. FIG. 95. Needle grass, Aristida oligantha. Plant, X i ; glumes and floret, X 2. GENERA OF GRASSES OF THE UNITED STATES. 165 The species of Aristida are of distinctly minor importance for for- age except in the Southwest, where several species, such as A. longi- seta, are eaten by stock before the flowers are produced. The annual species of the Eastern States are often found on open sterile soil, and hence are called poverty grass, a name applied also to annuals of other genera. 6. NAZIEAE, THE CURLY-MESQUITE TRIBE. 78. NAZIA Adans. (Tragus Hall.) Spikelets 1 -flowered, in small spikes of 2 to 5, the spikes sub- sessile, falling entire, the spikelets sessile on a very short zigzag rachis, the first glumes small, thin, or wanting, appressed to the rachis, the second glumes of the two lower spikelets strongly convex with 3 thick nerves bearing a row of squarrose, stout hooked prickles along each side, the two second glumes forming the halves of a little bur, the upper 1 to 3 spikelets reduced and sterile ; lemmas and palea thin, the lemma flat, the palea strongly convex. Low annual grasses, with flat blades and terminal inflorescence, the burs or spikes rather closely arranged along an elongate, slender axis. Species three, in the tropical regions of both hemispheres ; two species being introduced in the southern United States. Type species: Cenchrus racemosus L. Nazia Adans., Fam. PI. 2: 581. 1763. The genus is based on Cenchrus racemosus L. Trains Hall., Stirp. Helv. 2: 203. 1768. Haller cites pre-Linnsean authors who connect Tragus with Cenchrus racemosus L. Lappago Schreb., Gen. PI. 55. 1789. A new name is proposed for Tragus Hall. Echisachys Neck., Elem. 3: 228. 1790. No species are given. The author cites " Cenchrus Lin.," but his description shows that it is Linnseus's first species, Cenchrus racemosus, that he is renaming. Nazia racemosa (L.) Kuntze, with 3 to 5 spikelets in each cluster, the lower about 4 mm. long, is found in open ground from Texas to Arizona, and N. aliena (Spreng.) Scribn. (fig. 96), with two spike- lets in each cluster, the lower 2 to 3 mm. long, here and there through the Southern States to Arizona. They are somewhat weedy grasses of no economic importance. 79. OSTEBDAMIA Neck. (Zoysia Willd.) Spikelets 1 -flowered, laterally compressed, appressed flatwise against the slender rachis, glabrous, disarticulating below the glumes; first glume wanting; second glume coriaceous, mucronate, or short-, awned, completely infolding the thin lemma and palea, the palea sometimes obsolete* 166 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. Perennial low grasses with creeping rhizomes, short, pungently pointed blades, and terminal spikelike racemes, the spikelets on short appressed pedicels. Species about five, southeastern Asia to New Zealand. Type species: Agrostis matrella L. Osterdamia Neck., Elem. Bot. 3: 218. 1790. In a note appended to the para- graph on Agrostis, Necker states, "Agrostis matrella Lin. species distincta, agrostidis proxima, quam osterdamiam appellamus, char- actere sequenti." Although Osterdamia, Agrostis, Milium, and many other groups are called by Necker species of his genus Achyrophyton, these so-called species are the equivalent of the genera of his contemporaries and are usually so recog- nized by botanical writers. Zoysia Willcl., Ges. Naturf. Freund. Berlin, Neue Schrift. 3: 440. 1801. Type and only species, Z. pun (/ens Willd. Matrella Pers., Syn. PI. 1: 73. 1805. Type species. Affront!* juncca Lam., the only species described. Several years ago a species of this genus was introduced into the United States as a lawn grass under the names Korean lawn grass and Jap- anese lawn grass. It AT as recommended for the South- ern States and was said to be hardy as far north as Connecti- cut. 1 The species then intro- FIG. 96. Nazia aliena. Plant, X I ; group of spikelets (spike) and single spikelet, X 5. duced appears to be Osterdamia japonica (Steud.) Hitchc. (Zoysia japonica Steud.). Recently a fine-leaved species, Osterdamia tenui- folia (Willd.) Kuntze, has been introduced into Florida and has given favorable results. The original species, 0. matrella (L.) Kuntze (fig. 97), manila grass, is common in the Philippine Islands. 1 Scribner, U. S. Dept. Agr., Div. Agrost. Bull. 3: 95. 1896. GENERA OF GRASSES OF THE UNITED STATES. 167 80. HILAEIA H. B. K. Spikelets sessile, in groups of 3, the groups falling from the axis entire, the central spikelet (next the axis) fertile, 1-flowered, the 2 lateral spikelets staminate, 2-flowered ; glumes coriaceous, those of the 3 spikelets forming a false involucre, in some species connate at the base, more or less asymmetric, usually bearing an awn on FIG. 97. Manila grass, Osterdamia matrella. Plant, X I ; spikelet, X 10 ; floret with caryopsis, the palea obsolete, X 10. one side from about the middle; lemma and palea hyaline, about equal in length. Perennial low grasses, the groups of spikelets appressed to the axis, in terminal spikes. Species five, in arid regions, southwestern United States to Central America, all but one found within the limits of the United States. Type species: Hilaria cenchroides H. B. K. Hilaria H. B. K., Nov. Gen. and Sp. 1 : 116. 1816. Only one species described. 168 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. Pleuraphis Torr., Ann. Lye. N. Y. 1: 148, pi. 10. 1824. Type species P. jamesii Torr., the only one described. Hexarrhena Presl, Rel. Haenk. 1: 326, pi. 45. 1830. Type species H. cen- chroides Presl, the only one described. This is the same as Hilaria cen- chroides. FIG. 98. Curly mesquite, Hilaria belangeri. Plant, X 1 ; single spike, X 1 ; group of spikelets seen from front or outside, showing staminate spikelets in front and top of fertile spikelet behind, X 5 ; same group from behind or next the axis, showing the fertile spikelet in front and the two staminate spikelets behind, X 5 ; fertile spikelet as seen from the inside, X 5 ; fertile floret, X 5 ; staminate spikelet, X 5. Schleropelta Buckl., Prel. Rep. Geol. and Agr. Surv. Tex. App. 1. 1866. A single species is included, S. stolonifera Buckl., which is the same as Hilaria lelangeri Steud. Hilaria belangeri Steud. (fig. 98) is a common grass on the Great Plains of Texas and northern Mexico. In Texas it is called curly GENERA OF GRASSES OF THE UNITED STATES. 169 mesquite. It is a low grass, forming wiry stolons that in favorable soil produce a close, firm sod. The flowering culms are a few inches high and terminate in a short spike. Curly mesquite is an important grazing grass of the uplands of Texas. Our species has commonly been referred to the related, H. cenchroides^ of Mexico. Hilaria jamesii (Torr.) Benth. (fig. 99), an erect grass about a foot high, with glumes narrowed above, is found from Wyoming to Texas and southern California. This is called galleta grass in New Mexico. HUaria mutica (Buckl.) Benth., found from Texas to Ari- zona, differs from the preceding in having some of the glumes broad- ened above. This species is sometimes called tobosa grass. Hilaria rigida (Thurb.) Benth., with felty pubescent branched culms, is found from Utah to southern California. This also is called galleta grass. All the species of Hilaria are important range grasses. The last three species, with scaly rhizomes instead of stolons and with glumes bearing an awn on one side, compose Pleuraphis, held by some as a genus distinct from Hilaria. 81. AEGOPOGON Humb. and Bonpl. Spikelets short-pedicellate, in groups of 3, the group short- pedunculate, spreading, the peduncle disarticulating from the axis and forming a pointed stipe below the group, this falling entire; central spikelet shorter pedicellate, fertile, the 2 lateral ones longer pedicellate and staminate or neuter; glumes membranaceous, notched at the apex, the midnerve extending into a point or awn ; lemma and palea thinner than the glumes, extending beyond them, the lemma 3-nerved, the central nerve and sometimes also the lateral ones extend- ing into awns, the palea 2-awned. Annual low, lax grasses, with short, narrow, flat blades and loose racemes of delicate flower clusters. Species three, Arizona to Bolivia, one within the United States. Type species : Aegopogon cenchroides Humb. and Bonpl. Aegopogon Humb. and Bonpl. ; Willd. Sp. PI. 4 : 899. 1806. Only one species is described. Hymenothecium Lag., Elench. PI. 7. 1816. In the Elenchus, a list of seeds, occurs Hymenothecium tenellum Lag. based on Cynosurus tenellus Cav. The genus was published as new by Lagasca in Genera et Species Plantarum, a work appearing in the same year as the preceding but supposed to be some- what later. In this work (p. 4) four species are given, H. unisetum, H. tenellum, H. trisetum (Cynosurus gracilis Cav.), and H. quinquesetum. Cy- nosurus tenellus Cav. is accepted as the type. Schellingia Steud., Flora 33: 231, pi. 1. 1850. -Type, 8. tenera Steud., the only species described. This is Aegopogon cenchroides. The only species in the United States is Aegopogon tenellus (Cav.) Trin. (fig. 100), a Mexican species extending into southern Arizona. It is a pretty little grass, but is of no economic importance. 170 BULLETIN 7*72, U. S. DEPARTMENT OF AGRICULTURE. FIG. 99. Galleta grass, Jlilaria jamesii. Plant, X \ ; single spike, X 1 ; two views of group of spikelets, the lower a dorsal view, the upper a ventral view, X 5 ; staminate spikelet (below), X 5; fertile spikelet seen from the inside and fertile floret (above), X 5. GENERA OF GRASSES OF THE UNITED STATES. 7. CHLORIDEAE, THE GRAMA TRIBE. 82. LEPTOCHLOA Beauv. 171 Spikelets 2 to several flowered, sessile or short-pediceled, approxi- mate or somewhat distant along one side of a slender rachis, the rachilla disarticulating above the glumes and between the florets; glumes unequal or nearly equal, awnless or mucronate, 1-nerved, FIG. 100. Aegopogon tcnellus. Plant, X I ; group of spikelets, X 5 ; lateral spikelet, X 10 ; central (long-awned) spikelet, X 10. usually shorter than the first lemma ; lemmas obtuse or acute, some- times 2-toothed and mucronate or short-awned from between the teeth, 3-nerved, the nerves sometimes pubescent. Annual or perennial grasses, with flat blades and numerous spikes or racemes scattered along a common axis forming a long or some- 172 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. times short panicle. Species probably 20, in the warmer regions; 10 species in the United States, mostly in the Southern and South- western States. Type species: Cynosnrus virgatus L. Leptochloa Beauv., Ess. Agrost. 71, 166, pi. 15, f. 1. 1812. Beauvois includes three species, Cynosnrus capiltoceus, Eleusine flliformis, and E. virgata, all of which appear in the index under Leptochloa. The third species is figured and hence is selected as the type. Diplachne Beauv., Ess. Agrost. 80, pi. 16, f. 9. 1812. The type is Festuca fascicularis Lam., the only species mentioned. This is figured by Beauvois. Rabdochloa Beauv., Ess. Agrost. 84, pi. 17, f. 3. 1812. Beauvois includes Cynosurus monostachyos, C. I'irgatus, C. domingensis, C. cruciatus, and C. mucronatus, the last two with question. The species figured, C. domingensis, in the explanation to the plates called Rabdochloa domingensis, is selected as the type. Oxydenia Nutt., Gen, PI. 1: 76. 1818. Only one species included, O. at- tenuata, which is Leptochloa filiformis. Some authors * recognize Diplachne as a distinct genus, including Leptochloa fascicularis, L. floribunda, and L. dubia. In this group the spikelets are some- what pediceled and are less distinctly arranged in one-sided spikes. Those who recognize the genus place it in the tribe Festuceae. Leptochloa filiformis (Lam.) Beauv. (fig. 101) is an annual with papillate-pilose sheaths, small spikelets, the awnless florets shorter than the glumes, and numerous very slender spikes 3 to 6 inches long arranged in a panicle as much as a foot long. This is a weed in cultivated soil from Virginia to Florida and California; common also in the Tropics; sometimes called red sprangle-top. Leptochloa fascicularis (Lam.) Gray is a smooth, erect or pros- trate annual with several-flowered spikelets, the awned florets longer than the glumes; found in ditches and brackish meadows from Massachusetts to Florida and New Mexico. The other species are more local. Two perennials, L. domingensis (Jacq.) Trin. and L. virgata (L.) Beauv., are tropical species which reach the United States in southern Florida and southern Texas, respectively. Leptochloa dubia (H. B. K.) Nees, a perennial with comparatively few spikes and broad lemmas notched at the apex, the nerves glabrous (the margin pubescent), is found in Florida and from Texas to New Mexico. In the Southwest it is called sprangle or sprangle-top and Texas crowfoot, and it is important as a forage grass. For a revision of the species of Leptochloa found in the United States, see Hitchcock, U. S. Dept. Agr., Bur. PL Ind. Bull. 33. 1903. S3. TRIPOGOX Roth. Spikelets several-flowered, nearly sessile, and appressed in two rows along one side of a slender rachis, the rachilla disarticulating above the glumes and bet\veen the florets; glumes somewhat unequal, acute or acuminate, narrow, 1 -nerved; lemmas narrow. 3-nerved, 1 Nash in Small, Fl. Southeast. U. S. 145, 1900 ; in Britt. and Brown, Illustr. FL, ed. 2, 1:236. 1913. GENERA OF GRASSES OF THE UNITED STATES 173 FIG. 101. Red sprangle-top, Leptochloa filiformis. Plant, X i ; spikelet and floret, X 10. 174 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. bearing at the base a tuft of long hairs, bifid at the apex, the mid- nerve extending as a short awn. Our species is a low, tufted perennial, with capillary blades and slender solitary spikes, the spikelets somewhat distant. Species about nine, East Indian and African except one American. Type species: Tripogon bromoifles Roth. Tripogon Roth; Roem. and Schult, Syst. Veg. 2: 600. 1817. Only one species described. The American species, Tripogon spica- tus (Xees) Ekman (Leptochloa spicata Scribn.) (fig. 102), is found on sterile hills in Texas and northern Mexico, Cuba, and South America. It is of no im- portance agriculturally. 84. ELEUSINE Gaertn. Spikelets few to several flowered, compressed, sessile and closely im- bricate, in two rows along one side of a rather broad rachis, the latter not prolonged beyond the spikelets; rachilla disarticulating above the FIG. 102. Tripogon spicatus. Plant, x i ; spikelet and floret, X 5. glumes and between the florets, glumes unequal, rather broad, acute 3 1-nerved, shorter than the first lemma ; lemmas acute, with 3 strong green nerves close together forming a keel, the uppermost somewhat reduced ; seed dark brown, roughened by fine ridges, loosely inclosed in the thin pericarp. Annual grasses, with two to several rather stout spikes, digitate at the summit of the culms, sometimes with one or two a short dis- GENERA OF GRASSES OF THE UNITED STATES. 175 tance below, or rarely with a single terminal spike. Species about six, in the warm regions of the Eastern Hemisphere, one a common introduced weed in America. Type species: EJeusine coracana Gnertn. Eieusine Gaertn., Fruct. and Sem. 1 : 7, pi. 1, f. 11. 1788. Two species are described, E. coracana and E. indica. The first, being figured, is selected as the type. Eleusine indica (L.) Gaertn. (fig. 103) is a common garden and roadside weed throughout the warmer parts of America, extending northward to Illinois and Massachusetts. It is usually spreading or prostrate, with two to several spikes, or rarely one. This species is sometimes called goose-grass and yard-grass. The type species of the genus, Eieusine coracana Gaertn., is culti- vated in the Tropics of the Old World for the seed, which is used for human food by the poor or primitive people. It differs from E. indica in its larger size, stouter, often incurved spikes, and globose seed. 85. DACTYLOCTENITJM Willcl. Spikelets 3 to 5 flowered, compressed, sessile and closely imbricate, in two rows along one side of the rather narrow flat rachis, the end projecting in a point beyond the spikelets; rachilla disarticulating above the first glume and between the florets; glumes somewhat un- equal, broad, 1-nerved, the first persistent upon the rachis, the second mucronate or short-awned below the tip, deciduous; lemmas firm, broad, keeled, acuminate or short-awned, 3-nerved, the lateral nerves indistinct, the upper floret reduced; the palea about as long as the lemma ; seed subglobose, ridged or wrinkled, inclosed in a thin, early- disappearing pericarp. Annual or perennial grasses, with flat blades and two to several short thick spikes, digitate and widely spreading at the summit of the culms. Species three, in the warmer parts of the Eastern Hemi- sphere, one a common weed in tropical America. Type species: Cynosurus aegyptius L. Dactyloctenium Willd., Enum. PI. 1029. 1809. Willdenow describes but one species, D. aegyptiacum, based on Cynosurm aegyptius L. Our only species is Dactyloctenium aegyptium (L.) Richt. (D. aegyptiacum Willd.) (fig. 104), a tropical weed which extends northward to New York and Illinois. It is a prostrate annual with 2 to 5 spikes, often forming mats rooting at the nodes. Sometimes called crowfoot grass. 86. CAPRIOLA Adans. (Cynodon Rich.) Spikelets 1 -flowered, awnless, sessile in two rows along one side of a slender continuous rachis, the rachilla disarticulating above the glumes and prolonged behind the palea as a slender naked bristle, 176 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE, Tic. 103. Goose-grass, Eleusine indica. Plant, X i ; spikelet, floret, and seed (without pericarp), X 5. GENERA OF GRASSES OF THE UNITED STATES. 177 this sometimes bearing a rudimentary lemma ; glumes narrow, acumi- nate, 1-nerved, about equal, shorter than the floret; lemma strongly FIG. 104. Crowfoot grass, Dactyloctenium aegyptium. Plant, X i ; spikelet, floret, and seed (without pericarp), X 5. compressed, pubescent on the keel, firm in texture, 3-nerved, the lateral nerves close to the margins. 97769 19 Bull. 772 12 178 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. Perennial, usually low grasses, with creeping stolons or rhizomes, short blades, and several slender spikes digitate at the summit of the upright flowering stems. Species six, of which three are Aus- tralian, one species widely dis- tributed in the warmer regions of the globe. Type species: Panicum dacty- lon L. Capriola Adans., Fam. PI. 2: 31, 532. 1763. The genera are indi- cated and distinguished by Aclanson in a much abbreviated and often un- satisfactory manner. The tabular arrangement of the genera of Phal- arides, his first section of the grass family or Gramina, includes Cap- FIG. 105. Bermuda grass, Capriola dactylon. Plant, floret, X 5. X 2 ; spikelet and two views of riola, with the following diagnosis, interpreting the table : Summit of leaf sheath hairy ; flowers in digitate spikes ; glumes laterally compressed ; lemma awn less. In the index there is given as a synonym under Capriola, " Gramen dactylon Offic." The last phrase appears in the first edition of the Species Plantarum 1 in the synonymy under Panicum dactylon as " Gramen dactylon, radice repente. s. officinarum. Scheuch. gram. 104," thus connecting Capriola Adans. with Panicum dactylon. Cynodon Rich. ; Pers., Syn. PI. 1: 85. 1805. Only one species described, C. dac- tylon, based on Panicum dactylon L. The only species in Xofth America is Capriola dactylon (L.) Kuntze (fig. 105), commonly known as Bermuda grass. This is a ., Sp. PL 58. 1753. GENERA OF GRASSES OF THE UNITED STATES. 179 native of the Mediterranean region, but is common in the southern United States, extending north to Maryland, southern Kansas, and the interior valleys of California. Bermuda grass is the most important pasture grass of the South- ern States, and is also widely utilized there as a lawn grass. On alluvial ground it may grow sufficiently rank to be cut for hay. It propagates readily by its rhizomes and stolons and on this account may become a pestiferous weed in cultivated fields. This grass is known also as wire-grass (especially the weedy form in fields), Ba- hama grass in the West Indies, and manienie in the Hawaiian Islands. A. larger form, Capriola dactylon maritima (H. B. K.) Hitchc. (Cynodon maritimus H. B. K.), is found along the seacoast of Florida. 87. WILI/KOMMIA Hack. Spikelets 1-flowered, dorsally compressed, sessile in two rows on one side of a slender rachis and appressed to it, the rachilla some- what lengthened below and above the second glume, disarticulating just above it, not prolonged above the floret; glumes thin, the first narrow, about two-thirds as long as the second, nerveless, obtuse, the second 1-nerved, subacute; lemma about as long as the second glume, awnless, 3-nerved, the lateral nerves near the margin, the back of the lemma sparingly pubescent between the nerves, the mar- gins densely covered with silky hairs; palea 2-nerved, the nerves densely silky hairy. Annuals or perennials, with several short spikes scattered along a main axis; our species, a low, tufted perennial. Species four; three in South Africa, one in Texas. Type species: Willkommia sarmcntosa Hack. Willkommia Hack., Verh. Bot. Ver. Brandenburg 30: 145. 1888. Hackel de- scribes two species, W. sarmentosa, a perennial, and W. annua, ,an annual, both from German Southwest Africa. The first species is selected as the type. Willkommia texana Hitchc. (fig. 106), confined to a few localities in Texas, in alkali spots in prairies and openings in woods, has no agricultural importance. 88. SCHEDONNARDUS StCUd. Spikelets 1-flowered, sessile and somewhat distant in two rows on one side of a slender, continuous 3-angled rachis, appressed to its slightly concave sides, the rachilla disarticulating above the glumes, not prolonged; glumes narrow, stiff, somewhat unequal, acuminate, 1-nerved ; lemmas narrow, acuminate, a little longer than the glumes, 3-nerved. A low, tufted perennial, with stiff, slender, divergent spikes ar- ranged rather remotely along a common axis. Species one, on the Great Plains of the United States and in Argentina. 180 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. Type species : Schedonnardus texanus Steud. Schedonnardus Steud., Syn. PI. Glum. 1:146. 1854. A single species de- scribed, S. texanus, based on Drumiuond's no. 360 from Texas. This is /S. paniculatus (Nutt.) Trel. (Lcp- turns paniculatus Nutt.). Spirochloe Lunell, Amer. Midi. Nat. 4: 220. 1915. Pro- posed for " Schedonnardus Steud ... not thought per- missible, being built on Nardus." Schedonnardus panicu- latus (fig. 10T), the only species of the genus, is found on prairies and plains from Montana and Illinois to Texas. The axis of the inflorescence elon- gates after flowering, be- coming 1 to 2 feet long, curved in a loose spiral. The whole breaks away at maturity and rolls before the wind as a tumbleweed. The species is a forage grass, but the plants are low and in the main form only an inconsiderable pro- portion of the total forage. 89. BECKMANNIA Host. Spikelets 1-flowered, rarely 2-flowered, laterally compressed, subcircular, nearly sessile and closely imbricate, in two rows along one side of a slender continuous rachis, disartic- ulating below the glumes, FIG. 106. Willkommia texana. Plant, X I ; two views of spikelet and two views of floret, X 5. GENERA OF GRASSES OF THE UNITED STATES. 181 falling entire; glumes equal, inflated, obovate. 3-nerved, rounded above but the apex apiculate; lemma narrow, 5-nerved, acuminate, about as long as the glumes; palea 2- nerved, nearly as long as the lemma. Aa erect, rather stout annual, with flat blades and nu- merous short ap- pressed spikes in a narrow more or less interrupted panicle. Species one, in the cooler parts of America and Eur- asia. Type species : PJialaris erucae- fonnis L. Beckmannia Host, Gram. Austr. 3: 5, pi. 6. 1805. Only one species described. Beckmannia erueaeformis (L.) Host (fig. 108) is a marsh plant, found from Iowa to California and Alaska where it is often called slough-grass. It is FIG. 107. Schedonnardus t> aniculatus. palatable to Stock, is Plant, X I ; spikelet and floret, X 5. r 182 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. times sufficiently abundant locally to be an important forage grass, and is not infrequently used for hay. The European form has 2-flowered spikelets. 90. SPARTINA Schreb. Spikelets 1-flow- ered, much flattened laterally, sessile and usually closely im- bricate, on one side of a continuous ra- chis, disarticulating below the glumes, the rachilla not pro- duced beyond the floret; glumes keeled, l-nerved 5 FIG. 108. Slough-grass, Beckmannia erucaeformis. X 5. Plant, X spikelet and floret, GENERA OF GRASSES OF THE UNITED STATES. 183 acute or short-awned, the first shorter, the second often ex- ceeding the lemma; lemma firm, keeled, the lateral nerves obscure, narrowed to a rather obtuse point; palea 2-nerved, keeled and flat- tened, the keel between or at one side of the nerves. Stout, erect, often tall perennials, with usually extensively creep- ing, firm, scaly rhizomes, long tough blades, and two to many ap- pressed or sometimes spreading spikes racemose on the main axis. Species about 14, all North American except two or three along the coast of Europe, Africa, and South America. Type species: Spartina schreberi Gmel, Spartina Schreb. ; Ginel., S-yst. Nat. ed. 13. 2 : 123. 1791. The genus was first described by Schreber in his Genera Plantarum, 1 but no species was mentioned. Ginelin merely assigns a specific name to the description given by Schreber. Spartina schreberi is not recognized by European botanists, but it doubt- less is the common European species, S. maritima (Curt.) Fernald (S. stricta Roth). Trachynotia Michx., Fl. Bor. Amer. 1: 63. 1803. Type species T. cyno- suroides. Michaux describes three species, T. cynosuroides, T. polystachya, and T. juncea. The first species described is what is now called Spartina michauxi- ana Hitchc., but the synonym, Dactylis cynosuroides L., from which the specific name is taken, shows that Michaux had misapplied the name. The second spe- cies, T. polystachya, is Dactylis cynosuroides L., now called Spartina cynosu- roides (L.) Roth. Michaux remarks that this may be only a variety of the first species. It appears then that to Michaux the first species typifies the genus, and hence is selected here as the type species. Limnetis Pers., Syn. PI. 1 : 72. 1805. Four species are described, L. pungens, L. juncea, L. cynosuroides, and L. polystachya. The first species, which is the same as Spartina maritima, is selected as the type, as that is a native of Europe and is indigenous from the standpoint of the author. The other three species are American. There are eight species in the United States. All but two are found on or near the coast. Spartina cynosuroides (L.) Roth, a stout grass as much as 9 feet tall, is found along the Atlantic coast. The com- monest coastal species is S. patens (Ait.) Muhl. (including S. juncea Michx.) , which covers vast areas of salt marsh from Newfoundland to Texas. This is a slender wiry species usually less than 3 feet tall, with only a few somewhat spreading spikes. Spartina alterniftora Loisel. and its two varieties, glabra (Muhl.) Fern, and pilosa (Merr.) Fern., also of the Atlantic coast, have stout stems and closely appressed spikes, forming a cylindric inflorescence. A somewhat local species, S. sp.irtinae (Trin.) Merr., is found on the Texas coast. Another local species, S. foliosa Trin., is found on the coast of California. The only species without well-marked rhizomes is S. ~ba~keri Merr., of the f resh- water marshes and low savannas of Florida and coastal Georgia. Two species are found in the interior of the United States. One, &. michauxiana Hitchc. (fig. 109), is common in marshes and sloughs from New England to the Great Plains. A second, S. gradlis Trin., is found in alkaline grassland in the Western States. The first of these is used for thatching sheds and covering hay stacks. The leaves of 1 Schreb. Gen. PI. 1: 43. 1789. 184 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE, FIG. 109.- Marsh-grass, Spartina michauxiana. Plant, X \ ; spikelet and floret, X 5. GENERA OF GRASSES OF THE UNITED STATES. 185 S. bakeri and S. patens jimcea (Michx.) Hitchc. are used for making brooms. The marsh hay of the Atlantic coast, much used for bedding and packing, often consists largely of JS. patens. The species of Spartina are too coarse for forage. For a revision of the species found in the United States, see Mer- rill, U. S. Dept. Agr., Bur. PL Ind. Bull. 9. 1912. 91. CAMPULOSUS Desv. (Ctenium Panzer.) Spikelets several-flowered but with only one perfect floret, sessile and closely imbricate, on one side of a continuous rachis, the rachilla disarticulating above the glumes; glumes unequal, the first small, hyaline, 1-nerved, the second as long as the lemmas, firm, 3 to 4 nerved, bearing on the back a strong divergent awn ; lemmas rather papery, 3-nerved, villous on the lateral nerves and on the callus, bearing a short straight awn on the back just below the apex, the first and second lemmas empty, the third inclosing a perfect flower, the upper 1 to 3 empty and successively smaller. Erect, slender, rather tall perennials, with usually solitary, often curved spikes. Species about 12, in the warm regions, three being in the Eastern Hemisphere and the rest in America ; two species are found in the southeastern United States. Type species: Chloris monostachya Michx. Campulosus Desv., Nouv. Bull. Soc. Philom. Paris 2 : 189. 1810. Two species are mentioned, C. gracilior Desv. (based on Chloris monostachya Michx., which is Campulosus aroma ticus ), and C. hirsulus Desv. (based on Chloris falcata Swartz). The first is selected as the type. The second is now referred to Harpechloa. Ctenium Panzer, Denkschr. Baier. Akad. Wiss. Miinchen 4 : 288, pi. 13. 1813. (Ideeli Gatt. Graser, 38.) Only one species is described, Chloris monostachya Michx., to which Panzer gives the name Ctenium carolinianum. Monocera Ell., Bot. S. C. and Ga. 1: 176. 1816. A single species, based on Aeoilops aromaticum Walt., is included. Monathera Raf., Amer. Month. Mag. 4: 190. 1819. "Monocera Elliott . . . must be changed, because there is already a genus of shell of the same name." Our two species are confined to the Southeastern States, one of them, Campulosus floridanm Hitchc., to Florida, the other, C. aro- maticus (Walt.) Trin. (fig. 110), called toothache grass, extending from North Carolina along the Coastal Plain to Louisiana. Both species are rather infrequent and neither is of importance agri- culturally. 92. GYMNOPOGON Beauv. Spikelets 1 or rarely 2 or 3 flowered, nearly sessile, appressed and usually remote in two rows along one side of a slender continuous rachis, the rachilla disarticulating above the glumes and prolonged behind the one or more fertile florets as a slender stipe, bearing a rudiment of a floret, this sometimes with one or two slender awns ; 186 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. glumes narrow, acuminate, 1 -nerved, usually longer than the floret; lemmas narrow, 3-nerved, the lateral nerves near the margin, the FIG. 110. Toothache grass, Campulosus aromaticus. Plant, X \ ', splkelet and fertile floret (palea side up), X 5. apex minutely bifid, bearing between the teeth a slender awn, or rarely awnless. GENERA OF GRASSES OF THE UNITED STATES. 187 Perennial or rarely annual grasses, with short, flat, stiff blades, numerous stiff, slender, divergent spikes loosely scattered along the upper part of the culm, or sometimes aggregate toward the summit, the spikes often deflexed at maturity. Species 10, nearly all Amer- ican ; 3 species in the southeastern United States. Type species : Andropogon ambiguus Michx. Gymnopogon Beauv., Ess. Agrost. 41, pi. 9, f. 3. 1812. Beauvois mentions one species, Andropogon ambiguus Michx., which is figured. In the description of the plate the name given is Gymnopogon, raceinosus. Alloiatheros Ell., Bot. S. C. and Ga. 1: 146. 1816. This name is casually mentioned by Elliott in the description of Andropogon ambiguus: "I once in- tended to insert it as a distinct genus under the name of Alloiatheros, from the dissimilarity of its awns, not only in position but in figure." Anthopogon Nutt, Gen. PI. 1: 81. 1818. Based on Andropogon ambiguus Michx., which name Nuttall changes to Anthopogon lepturoides. The spikelets are usually 1-flowered and awned,but in G-ymnopogon chapmanianus Hitchc., of Florida, they are 2 to 4 flowered and awn- less. This species shows in its spikelet characters a transition to Leptochloa, but in habit it closely resembles the other two species of the United States. In G. foliosm (Willd.) Nees, of Porto Eico and South America, the rudiment bears two long awns. Our species are perennials, with an inflorescence of scattered spikes. Our commonest species is Gymnopogon ambiguus (Michx.) B. S. P. (fig. Ill) , found in sandy soil from New Jersey to Missouri and south to Florida and Texas. Another species, G. l>revifolius Trin., grows from New Jersey to Florida. This species differs from the preced- ing in having the rachis spikelet bearing only along the upper half . The species have no agricultural importance. 93. CHLOBIS Swartz. Spikelets with 1 perfect floret, sessile, in two rows along one side of a continuous rachis, the rachilla disarticulating above the glumes, produced beyond the perfect floret and bearing 1 to several reduced florets consisting of empty lemmas, these often truncate, and, if more than one, the smaller ones inclosed in the lower, forming a usually club-shaped rudiment; glumes somewhat unequal, the first shorter, narrow, acute; lemma keeled, usually broad, 1 to 5 nerved, often villous on the callus and villous or long-ciliate on the keel or marginal nerves, awned from between the short teeth of a bifid apex, the awn slender or sometimes reduced to a mucro, the sterile lemmas awned or awnless. Perennial or sometimes annual, tufted grasses, with flat blades and two to several often showy and feathery spikes aggregate at the summit of the culms. Species about 60, in the warmer regions ; 15 in the southern United States. Type species : Agrostis cruciata L. Chloris Swartz, Prod. Veg. Ind. Occ. 25. 1788. Swartz describes five species, C, cruciata, C. ciliata, C. petraea, C. polydactyla, and C. radiata, all from the 188 BULLETIN 772, U. S. DEPARTMENT OP AGRICULTURE. FIG. 111.- Gymnopogon ambigitus. Plant, X \ ', spikelet and floret, X 5. GENERA OF GRASSES OF THE UNITED STATES. 189 West Indies. The second and third are described as new ; the others are based on Linnsean species, the first on Agrostis cruciata, the fourth "on Andropogon polydactylon, and the fifth on Agrostis radiata. The first species is selected as the type. Eustachys Desv., Nouv. Bull. Soc. Philom. Paris 2: 188. 1810. One species is described, E. petraeus, based oil Chloris petraea Swartz. Eustachys, recog- nized by some American botanists as distinct, forms a section of the genus Chloris and includes four species, C. petraea, C. glauca (Chapm.) Vasey, C. floridana (Chapm.) Vasey, and C. neglecta Nash. The group differs from Euchloris in having the lemmas short-awned or mucronate, brown, and rather firm in texture. Chlorostis Raf., Princip. Fondament. Somiologie 26, 29. 1814. Proposed change of name for Chloris Swartz, because of Chlora L. ( : an animal) . Several species are found on the plains of Texas, where they form an unimportant part of the forage for grazing animals. Chloris verticittata Nutt. and its allies are known as windmill grasses. The mature inflorescence, consisting of several slender, divergent spikes, breaks away from the plant and rolls before the wind as a tumble- weed. In the Southwestern States is found C. virgata Swartz (C. elegans H. B. K.) (fig. 112), a tuftecl annual, 1 to 2 feet high, with several pale or purplish, erect, feathery spikes 1 to 2 inches long. This species invades cultivated fields and sometimes becomes a rather common weed, especially in alfalfa fields. One species, C. gayana Kunth, a native of South Africa, is culti- vated to a limited extent as a forage grass. This species, called Rhodes grass, has been shown to have value as a meadow grass in the Southwestern States. In the Hawaiian Islands it is used on some of the ranches in the drier regions. Rhodes grass is a perennial, 2 to 3 feet high, producing long, stout, creeping, propagating stems or stolons and bearing at the summit of the flowering stems a close fan- shaped cluster of numerous spikes 2 to 4 inches long. For a revision of the species of Eustachys and Chloris found in the United States, see Nash, Bull. Torrey Club 25 : 432-450. 1898. 94. TRICHLORIS Fourn. Spikelets 1 to few flowered, nearly sessile, in two rows along one side of a continuous slender rachis, the rachilla disarticulating above the glumes and prolonged behind the uppermost perfect floret, bear- ing a reduced, usually awned floret; glumes unequal, acuminate, or short-awned, the body shorter than the lower lemma; lemmas nar- row, 3-nerved, the marginal nerves sometimes pubescent, these and the midnerve extending into awns, the central long and slender, the lateral often much shorter. Erect, slender, tufted perennials, with flat blades and numerous erect or ascending spikes, aggregate but scarcely digitate at the summit of the culms. Species two or three, in the dry regions of Texas and Mexico and also in Argentina. 190 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. Type species : Trichloris pluriflora Fourn. Trichloris Fourn., Mex. PI. 2: 142. 1886. Fournier includes two specie: T. fasciculata and T. pluriflora, both described as new. In the generic descrij FIG. 112. Chloris viryata. Plant X \ ; glumes and floret with rudiment, X i tion occurs the statement " flore summo tabescente mutico." Under the secon species one finds " flore summo mutico." From this it would appear tha T. pluriflora represented Fournier's idea of the genus; hence this species i selected as the type. GENERA OF GRASSES OF THE UNITED STATES. 191 Chloropsis Hack. ; Kuntze, Rev. Gen. PI. 2 : 771. 1891. The name was men- tioned by Hackel 1 as a synonym under Trichloris. Hackel also mentions Chloridopsis, both names having been used by gardeners for Trichloris blan- chardiana Hack, of Argentina. Kuntze changes the name Trichloris to Chlor opsis, because of the earlier Trichlora Baker. Both Trichlora and Trichloris may be considered valid, since they have different derivations and slightly different spellings. Since Kuntze adopts Hackel's name and since Hackel mentions Chloropsis blanchardiana, this species is selected as the type of Chloropsis. The two species of the United States, Trichloris mendocina (Phil.) Kurtz (T. fascieulata Fourn.) (fig. 113) and T. plwriflora Fourn., are found in the arid regions of northern Mexico and extend into western Texas, southern New Mexico, and southern Arizona. The first has spikelets with one perfect floret and a rudiment, each with three long awns; the second has spikelets with 3 to 5 florets, the upper one or two reduced, the lateral awns reduced or sometimes wanting. Neither is of importance agriculturally. 95. BOTJTELOUA Lag., the grama grasses. Spikelets 1 -flowered, with the rudiments of one or more florets above, sessile, in two rows along one side of the rachis; glumes un- equal, 1-nerved, acuminate or awn-tipped, the first shorter and nar- rower; lemma as long as the second glume or a little longer, 3-nerved, the nerves extending into short or often rather long awns, the in- ternerves usually extending into teeth; palea 2-nerved, sometimes 2-awned; rudiment various, usually 3-awned, a second rudimentary floret sometimes present. Perennial or sometimes annual, low or rather tall grasses, with two to several or many spikes racemose on a common axis, or sometimes solitary, the spikelets few to many in each spike, rarely solitary, pectinate or more loosely arranged and appressed, the rachis of the spike usually produced beyond the insertion of the spikelets. Spe- cies 38, all American and chiefly North American; 18 species found in the United States, mostly in open grassland of the southwestern States. Type species : Bouteloita racemosa Lag. liouteloua Lag., Varied. Cienc. Lit. and Art. 2 4 : 134. 1805. Lagasca gives five species, B. racemosa, B. hirsuta, B. barbata, B. simplex, and B. prostrata. All ;;re briefly described, except the last, which is mentioned by name only. The first species (which is the same as B. curtipendula) is selected as the type. In this work Lagasca spells the name of the genus " Botelua " and states that he names the genus in honor of the two brothers Boutelou. In a later work 2 Lagasca describes the genus under the name Bouteloua, and includes 10 species, the first of which is B. htysuta. The spelling Bouteloua is retained because it was corrected to this form by the author to correspond to the spelling of the personal name of the brothers Boutelou, and because this second spelling has been universally accepted by botanists. Atheropogon Muhl. ; Willd., Sp. PI. 4: 937. 1806. A single species is described, A. apludioides Muhl., which is Bouteloua curtipendula. Triathera Desv., Nouv. Bull. Soc. Philom. Paris 2: 188. 1810. Based on Aristida amtrwana L., which is Bouteloua americana (L.) Scribn., a West Indian species. *In Engl. and Prantl, Pflanzeafam. 2 2 : 59. 1887. 2 Gen. and Sp. Nov. 5. 1816. 192 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. FIG. 113. Trichloris inendoctna. Plant, X J ; glumes and floret with rudiment, X 5. GENERA OF GRASSES OF THE UNITED STATES. 193 Heterosteca Desv., Nouv. Bull. Soc. Philom. Paris 2: 188. 1810. Based on //. juncifolia, which is Bouteloua heterostega (Trin.) Griffiths, of the West Indies. Chondrosium Desv., Nouv. Bull. Soc. Philom. Paris 2 : 188. 1810. Based on Chloris procumbens Durand (Bouteloua procumbens). Polyodon H. B. K., Nov. Gen. and Sp. 1 : 174, pi. 55. 1816. Based on a single species, P. distichum H. B. K. Triaena H. B. K., Nov. Gen. and Sp. 1 : 178. 1816. A single species described, T. racem