AVENE& 



211 



having the caryopsis loosely and not permanently inclosed in the 

 nerved lemma. 



Avena fatua L. (Fig. 44). Wild oats. Differs from A. saliva 

 chiefly in the spikelet characters. Florets easily disarticulating, the 

 lemma beset with stiff usually brown hairs, 

 these more abundant at base, the teeth acute 

 as in A. saliva, the dorsal awn well developed, 

 over an inch long, geniculate, twisted at base, 

 usually brown. A common weed on the 

 Pacific coast and occasional elsewhere. 



Avena fatua glabrata 

 Peterm. Differs from A. fatua 

 in having nearly or quite gla- 

 brous lemmas. This form can 

 be distinguished from the usual 

 forms of A. saliva by the 

 strong awn and by the easily disarticulating 

 spikelets. 



Avena barbata Brot. Differs from A . fatua in 

 having more slender panicle branches and in the 

 awned teeth of the lemma. A common weed on 

 the Pacific coast, and a constituent of the wild 

 oats of that region. 



Avena sterilis L. Animated oats. Differs from 

 A. fatua in having larger spikelets, the glumes nearly 2 inches long, 

 and awns about 2 inches long. An occasional . weed and some- 

 times cultivated as a curiosity, the "seeds" moving about as the 

 awns twist and untwist. This motion is due to the absorption or 

 loss of moisture. 



240. Origin of the cultivated oats. Trabut has shown 

 that our cultivated oats are derived from at least three 

 wild species. Avena fatua is the parent of most of the 

 varieties cultivated in America, and in general the va- 

 rieties of temperate and mountain regions. The Algerian 

 oat grown in North Africa and Italy is derived from 

 Avena sterilis. A few varieties such as Avena strigosa, 

 adapted to dry countries, are descended from Avena 



FIG. 44. Avena 

 fatua. Spikelet and 

 a lower floret, XL 



