36 POACEAE. 



21. AVENA L. Oat. 



Annual or perennial grasses with generally flat leaves 

 and paniculate inflorescence. Spikelets 2-several-flow- 

 ered or rarely 1 -flowered; the lower flowers perfect, the 

 upper usually staminate. Glumes 4-many, the 2 outer 

 empty, somewhat unequal, membranous, persistent; 

 flowering glumes deciduous, rounded on the back, acute, 

 generally bearing a dorsal awn, apex often 2-toothed. 

 Palea narrow, 2-toothed. Stamens 3. Styles short, 

 distinct. Grain oblong, deeply furrowed, enclosed in 

 the glume and palea, free or sometimes adherent to the 

 latter. 



1. A. fatua L. (Wild Oat.) Culms usually tufted, 5-15 dm. 

 high; leaves scabrid, rather long and broad; panicle 1-4 dm. long, 

 its branches unequal, long filiform; spikelets drooping, 2-3-flowered; 

 empty glumes subequal, ovate-lanceolate, 20-25 mm. long, 9-11- 

 nerved; flowering glumes 18 mm. long, acute, bifid, yellowish hairy 

 especially below, 9-nerved; awn from near the middle of the glume, 

 1-2 cm. long, geniculate; palea 15 mm. long, hairy on the nerves. 



Very common in all the valleys and on grassy hills. Native of 

 southern Europe. 



la. A. fatua glabrata Peterm. (Bastard Oats.) Like the type 

 except that the flowering glumes are glabrous. In this respect 

 resembling A. sativa L., the cultivated oat, but it is easily dis- 

 tinguished from that by its longer and geniculate awn and wide, 

 9-nerved flowering glume. A. sativa is awnless or has a short 

 straight awn and a 7-nerved glabrous flowering glume. 



Occasional in valleys. San Bernardino, Parish; Inglewood. 



2. A. barbata Brot. Resembling fatua, but more slender, the 

 spikeletes smaller, mostly 2-flowered, the pedicels curved and 

 capillary; floral glume, clothed with stiff red hairs, the teeth acumi- 

 nate and ending in fine awns 4 mm. long. 



Less common than the last, but widely distributed over the 

 mesas and foothills of California. Best distinguished from fatua 

 by the teeth of the floral glume which are merely acute and not 

 awned in that species. 



22. DANTHONIA DC. Wild Oat-grass. 



Annual or perennial grasses with flat or convolute 

 leaves and contracted or open panicles. Spikelets 3- 

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

 nate; rachilla pubescent extending beyond the flowers. 

 Glumes 5-many, the 2 outer empty, keeled, acute, sub- 

 equal, persistent, generally extending beyond the upper- 

 most flowering glume; flowering glumes rounded on the 



