294 MISC. PUBLICATION 200, U. S. DEPT. OF AGRICULTURE 



3. Aira capillaris Host. (Fig. 583.) Resembling A. caryophyllea; 

 panicle more diffuse; spikelets 2.5 mm long, scattered at the ends of 

 the branches; lemma of lower floret awnless or with a minute awn 

 just below the apex, that of the upper floret 

 with an awn 3 mm long. © — Open ground, 

 Coastal Plain, Maryland to Florida and Texas; 

 Oregon and California, rare (fig. 584). 



Figure 582.— Distribution of 

 Aira caryophyllea. 



Corynephorus canescens (L.) Beauv. Low, 

 tufted annual resembling Aira caryophyllea, with 

 pale contracted panicle; lemmas membrana- 

 ceous, the awns jointed about the middle, the joint with a minute ring 

 of hairs, the lower part straight, brown, the upper slender, club-shaped. 

 O (Weingaertneria canescens Bernh.) — Ballast at Philadelphia and 

 Camden, N. J., on Marthas 

 Vineyard, and on Long Island ; 

 adventive from Europe. 



57. AVENA L. Oats 



Spikelets 2- to several- 

 flowered, the rachilla bearded, 

 disarticulating above the 

 glumes and between the florets ; 

 glumes about equal, membra- 

 naceous or papery, mostly 

 several-nerved, longer than the 

 lower floret, usually exceeding 

 the upper floret; lemmas in- 

 durate, except toward the sum- 

 mit, 5- to 9-nerved, bidentate 

 at apex, bearing a dorsal bent 

 and twisted awn (this straight 

 and reduced in Avena sativa). 

 Low or moderately tall annuals 



r»r» -ruvrwrminlc wirVi norrnw r\r Figure 583.— Aira capillaris. Panicle, X 1; spikelet and 

 VI peieiimtUb, i Willi litiiiuw ui florets, X 5. (Davis 2016, S. C.) 



open, usually rather few- 

 flowered panicles of usually large spikelets. 

 Avena, the old Latin name for oats. 



The most important species of the genus is A. sativa, the familiar 

 cultivated oat. Two other introduced species, 

 A. jatua and A. barbata, are known as wild oats 

 because of their close resemblance to the culti- 

 vated oat. These two species are common on 

 the Pacific coast where they are weeds but are 

 often 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 com- 

 mon varieties of this country and of temperate and mountain regions 

 in general are derived from A. Jatua. The Algerian oat grown in 

 North Africa and Italy and the ^red oat of our Southern States 



Type species, Avena sativa. 



Figure 584.— Distribution of 

 Aira capillaris. 



