28 



POACEAE. 



2. PoljTpogon littoralis Smith. Short- 

 AWNED OR Perennial Beard-grass. (Fig. 

 39.) Tufted, perennial, erect, 6'-2^° tall. 

 Leaves 6' long or less, 2"-4" wide; panicle 

 li'-6' long, moderately dense, dull, with 

 ascending branches 4"-10" long; outer 

 empty scales about Ij" long, scabrous, 

 bearing an awn of about the same length; 

 flowering scales awnless, much shorter than 

 the empty ones. 



Roadsides, waste and cultivated grounds. 

 Abundant. Introduced from Europe. Natural- 

 ized in the southern and western United States. 

 Flowers in summer and autumn. 



16. AVENA L. 

 Annual or perennial grasses with panicled, large spikelets. Spikelets 2- 

 several-flowered, the lower flowers perfect, the upper often imperfect or stami- 

 nate; scales 4-many, the 2 lower ones empty, sometimes unequal, membranous, 

 persistent, the flowering ones rounded on the back, acute, usually bearing a 

 dorsal awn and often 2-toothed at the apex, deciduous; palet narrow 2-toothed. 

 Stamens 3. Styles short, distinct; stigmas plumose. Grain oblong, deeply 

 furrowed. [Old Latin name for the Oat.] About 30 species, widely distributed 

 in temperate regions. Type species: Avena sativa L. 



"Flowering scales more or less hispid, the awn distinctly spiral. 

 Flowering scales glabrous, awnless or with a nearly straight awn. 



1. Avena f&tua L. Wild Oat. 

 (Fig. 40.) Culms l°-4° tall, erect, 

 simple, stout, smooth and glabrous. 

 Sheaths smooth, or scabrous at the sum- 

 mit, sometimes sparingly hirsute, the 

 lower often overlapping; leaves 3'-8' 

 long, l"-4" wide; panicle open, 4'-12' 

 in length, the branches ascending; spike- 

 lets 2-4-flowered, drooping; outer scales 

 f'-l' in length, smooth, enclosing the 

 flowering scales; flowering scales 6"-9" 

 long, with a ring of stiff brown hairs at 

 the base, pubescent with long rigid 

 brown hairs, bearing a long bent and 

 twisted awn. 



Collected by F. S. Collins at Flatt's, 

 1914. Introduced. Native of the Old 

 World. Widely naturalized in the western 

 United States. 



1. A. fatua. 



2. A. sativa. 



