300 



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



upper floret ; lemmas indurate, except toward the summit, 5- to 9-nerved, bi- 

 dentate, bearing a dorsal bent and twisted awn (straight and reduced in 

 Avena sativa), the awn in age commonly breaking at the bend. Low or 

 moderately tall annuals, with narrow or open, usually rather few-flowered 

 panicles of large spikelets. Type species, Avena sativa. 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. fatua and A. barbata, are known as wild 

 oats because of their close resemblance to the cultivated oat. These two 

 species are common on the Pacific coast where they 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 common varieties of this country and of temperate and mountain regions 

 in general are derived from A. fatua. The Algerian oat grown in North Africa 

 and Italy and the red oat of our Southern States (A. byzantina K. Koch) are 

 derived from A. sterilis. A few varieties adapted to dry countries are de- 

 rived from A . barbata. 



Teeth of lemma setaceous; pedicels curved, capillary 3. A. barbata. 



Teeth of lemma acute, not setaceous; pedicels stouter. 



Spikelets mostly 2-flowered, the florets not readily separating; awn usually straight or 



wanting; lemmas glabrous - - 2. A. sativa. 



Spikelets mostly 3-flowered, the florets readily separating; awn stout, geniculate, twisted; 

 lemmas clothed with stiff brown hairs (hairs sometimes white or scant). 



1. A. FATUA. 



1. Avena fatua L. Wild oat. (Fig. 

 407, .4.) Culms 30 to 75 cm. tall, 

 erect, stout; leaves numerous, the 

 blades flat, usually 4 to 8 mm. wide, 

 scabrous; panicle loose and open, the 

 slender branches usually horizontally 

 spreading; spikelets usually 3-flow- 

 ered; glumes about 2.5 cm. long; ra- 

 chilla and lower part of the lemma 

 clothed with long stiff brownish, or 

 sometimes whitish, hairs, these some- 

 times scant; florets readily falling 

 from the glumes; lemmas nerved 

 above, about 2 cm. long, the teeth 

 acuminate, not setaceous; awn stout, 

 geniculate, twisted below, 3 to 4 cm. 

 long. O — Cultivated soil and 

 waste places; introduced from Eu- 

 rope; rare in the Eastern States; 

 Maine to Pennsylvania, Missouri and 

 westward, a common weed on the 

 Pacific coast. Seed used for food by 

 the Indians. 



Avena sterilis L. Animated oats. 

 Resembling A. fatua, the spikelets 3.5 

 to 4.5 cm. long, the awns 5 to 7 cm. 

 long. O — Sometimes cultivated 

 as a curiosity, occasionally spontane- 

 ous. When laid on a moist surface the 



fruits twist and untwist as the awns 

 lose or absorb moisture. Sometimes 

 used as flies in fishing, the spikelets 

 jerking as the awns untwist. 



2. Avena sativa L. Oat. (Fig. 407, 

 B.) Differing from A. fatua in having 

 mostly 2-flowered spikelets, the flo- 

 rets not readily separating from the 

 glumes; lemmas glabrous; awn usu- 

 ally straight, often wanting. O — 

 Commonly cultivated and occasion- 

 ally escaped. In A. nuda L., naked 

 oat, the caryopsis readily separates 

 from the lemma and palea. A. brevis 

 Roth is a form with smaller spikelets, 

 the lemmas plump, awned. A. strigosa 

 Schreb. has a 1-sided panicle, the 

 lemmas scabrous toward the apex, 

 both florets awned. 



3. Avena barbata Brot. Slender 

 oat. (Fig. 408.) Differing from A. 

 fatua in the somewhat smaller, mostly 

 2-flowered spikelets on curved capil- 

 lary pedicels; lemmas clothed with 

 stiff red hairs, the teeth ending in fine 

 points 4 mm. long. O — A common 

 weed in fields and waste places, Wash- 

 ington and Oregon to Arizona and 

 California. 



