220 



GRAMINEAE. 



VOL. L 



54. ARRHENATHERUM Beauv. Agrost. 55. pi. n. f. 5. 1812. 



Tall perennial grasses, with flat leaf-blades and contracted or open panicles. Spikelets 

 2-flowered; lower flower staminate, upper perfect; rachilla extended beyond the flowers. 

 Scales 4, the 2 lower empty, thin-membranous, keeled, very acute or awn-pointed, unequal, 

 persistent, flowering scales rigid, 5~7-nerved, deciduous, the first bearing a long bent and 

 twisted dorsal awn, inserted below the middle, the second unawned; palet hyaline, 2-keeled. 

 Stamens 3. Styles short, distinct. Stigmas plumose. Grain ovoid, free. [Greek, referring 

 to the awn of the staminate scale.] 



Six species, natives of the Old World. Type species : Avena elatior L. 



i. Arrhenatherum elatius (L.) Beauv. Oat- 

 grass. Fig. 531. 



Avena elatior L. Sp. PI. 79. 1753. 



A. avenaceum Beauv. Agrost. 152. Name only. 1812. 



A. elatius Beauv.; M. & K. Deutsch. Fl. i: 546. 1823. 



Glabrous, culms 2-4 tall, erect, simple. Lower 

 sheaths longer than the internodes; ligule i" long; 

 blades 2^-12' long, i"-4" wide, scabrous; panicle 4'-i2' 

 in length, contracted, the branches erect, the lower i'-2 r 

 long; empty scales finely roughened, the second 4" long, 

 the first shorter; flowering scales about. 4" long. 



In fields and waste places, Newfoundland to Ontario and 

 Minnesota, south to Georgia and Tennessee and Nebraska. 

 Also on the Pacific Coast. Naturalized from Europe. Tall, 

 or False Oat-grass ; Pearl-, Hever-, Evergreen-, Button- or 

 Onion-grass ; Button-, Butter- or Onion-twitch ; Grass of 

 the Andes. June-Aug. 



55. DANTHONIA DC. Fl. Fran. 3 : 32. 1805. 



Mostly perennial grasses, with flat or convolute leaf- 

 blades and contracted or open panicles. Spikelets 

 3-many-flowered, the flowers all perfect, or the upper 

 staminate; rachilla pubescent, extending beyond the flowers. Scales 5-many, the 2 lower 

 empty, keeled, acute, subequal, persistent, generally extending beyond the uppermost flower- 

 ing one; flowering scales rounded on the back, 2-toothed, deciduous, the awn arising from 

 between the acute or awned teeth, flat and twisted at base, bent; palet hyaline, 2-keeled near 

 the margins, obtuse or 2-toothed. Stamens 3. Styles distinct. Stigmas plumose. Grain 

 free, enclosed in the scale. [Name in honor of Etienne Danthoine, a Marseilles botanist of 

 the last century.] 



A genus of about 100 species, widely distributed in warm and temperate regions, chiefly in 

 South Africa. Type species : Avena spicata L. 

 Spikelets, exclusive of the awns, less than Yz' long. 



Teeth of flowering scales merely acute, not awned; panicle contracted, spike-like, i. D. spicata. 

 Teeth of the flowering scales long-awned ; panicle commonly open, its branches spreading, 



and usually reflexed at flowering time. 

 Spikelets, exclusive of the awns, exceeding J^' long. 

 Panicle loose and open, green ; awns 5" long or more. 

 Foliage and flowering scales pubescent. 



Foliage glabrous ; flowering scales pubescent on margins and base only. 

 Panicle contracted, spike-like, dense, purple-variegated ; awns 3 "-4" long. 



i. Danthonia spicata (L.) Beauv. Common 

 Wild Oat-grass. Fig. 532. 



Avena spicata L. Sp. PI. 80. 1753. 



Danthonia spicata Beauv.; R. & S. Syst. 2: 690. 1817. 



Culms \-2\ tall, erect, simple, smooth and gla- 

 brous, nearly terete. Sheaths shorter than the inter- 

 nodes, glabrous or often sparingly pubescent below ; 

 lignle very short; blades rough, i" wide or less, 

 usually involute, the lower 4'-6' long, the upper 

 i '-2' long; inflorescence racemose or paniculate, i'-2' 

 in length, the pedicels and branches erect or ascend- 

 ing; spikelets 5-8-flowered; empty scales 4"-5" long, 

 glabrous ; flowering scales broadly oblong, sparingly 

 pubescent with appressed silky hairs, the teeth about 

 i" long, acute or short-pointed, the bent spreading 

 awn closely twisted at the base, loosely so above. 



In dry soil, Newfoundland to South Dakota, south 

 to North Carolina and Texas. Ascends to 3000 ft. in 

 Virginia. June-grass. July-Sept. 



2. D. compressa. 



3. D. sericea. 



4. D. epilis. 



5. D. intermedia. 



