28 POACEAE. 



the sheaths shorter than the internodes; panicle shining, 15-25 cm. long, rather 

 narrow, the branches suberect; lemmas 6-7 mm. long, the lower bearing a 

 long dorsal geniculate awn. Sparingly escaped from cultivation. 



46. MERATHREPTA. 



Flowers solitary or few in a small raceme or panicle; spikelets 

 3 to many-flowered, the flowers all perfect or the upper staminate; 

 rachilla pubescent, extending beyond the flowers; glumes keeled, 

 acute, subequal, persistent, generally extending beyond the 

 uppermost lemma; lemmas rounded on the back, 2-toothed, 

 deciduous, tha bent awn flat and twisted at the base, arising 

 from between the acute or awned teeth; palea hyaline, 2-keeled 

 near the margins, obtuse or 2-toothed ; grain free, enclosed in the 

 lemma. 



Spikelets in small racemes; leaves merely scabrous. M. calif arnica. 



Spikelets mostly solitary; leaves hairy. M. unispicata. 



Merathrepta californica (Boland.) Piper. Erect, 50-100 cm. tall; leaf 

 blades flat, scabrous; sheaths loose, shortly retrorse-pubescent, with a tuft 

 of hairs at the throat; spikelets 1-2 cm. long, 3-5 in a raceme, rarely more 

 numerous or even solitary, usually long-pedicelled; lemma long-ciliate below 

 the middle, two cleft at apex, bearing an awn of about equal length. Common 

 in low places. 



Merathrepta unispicata (Thurb.) Piper. Closely resembling M. californica 

 but not so large, 15-30 cm. tall; leaf blades sparsely hairy, the sheaths villose 

 with long white hairs; spikelets small, solitary. In dry soils, rare. 



47. AVENA. OATS. 



Annuals with large spikelets; inflorescence a panicle; spike- 

 lets 2-many-flowered ; lower flowers perfect, the upper often 

 staminate; glumes somewhat unequal, membranous, persistent; 

 lemmas deciduous, rounded on the back, acute, generally bearing 

 a dorsal awn; apex often 2-toothed; palea narrow, 2-toothed; 

 grain oblong, deeply furrowed, enclosed in the lemma and palea, 



free or sometimes adheren'c to the latter. 



^ 



Avena fatua glabrata Petermann. Smooth Wild Oat. Stems stout, pale, 

 smooth, 50-100 cm. tall, erect; leaf blades broad and flat, the sheaths about 

 equalling the internodes; panicle loose 15-30 cm. long; spikelets, including 

 awns, 3.5-^4 cm. long, erect or drooping, on slender branches; lemma smooth, 

 except the scabrous apex and the ring of stiff white hairs at the base, bearing 

 on the back a geniculate, stout, twisted awn below the 2-cleft apex. A trouble- 

 some weed in cultivated land. 



48. DESCHAMPSIA. 



Annuals or perennials; inflorescence a contracted or open 

 panicle; spikelets 2-flowered, both flowers perfect, the hairy 

 rachilla extending beyond the flowers or rarely terminated by a 

 staminate one; glumes keeled, acute, membranous, shining, 



