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A TEXT-BOOK OF GRASSES 



the lemmas, the latter being awnless or bearing a straight 

 awn. A wild species (A.fatua) differs in having the lemma 

 covered with brown hairs and in having a stout geniculate 

 twisted dorsal awn attached near the base. This species 

 is a native of Europe but is introduced on the Pacific 

 coast where it is a common weed known as wild oats and 

 where it is often used for hay. 



Avena sativa L. Cultivated oat. An- 

 nual; culms erect, tufted, smooth, 2 to 4 

 feet high; sheaths smooth, striate, the 

 lower rather papery; ligule membranace- 

 ous, truncate, 1 to 3 mm. long, toothed or 

 serrate, decurrent along the margin of the 

 sheath; blades flat, as much as 1 foot 

 long and ^2 inch wide, scabrous especially 

 on the margins; panicle open or more or 

 less contracted, erect or nodding, some- 

 times 1-sided, the pedicels thickened at 

 the apex; spikelets large, drooping, vari- 

 able in size but usually about % to 1 inch long, 

 the glumes strongly several - nerved, membra- 

 naceous, acuminate, scabrous, containing usually 

 2 florets, the lemmas smooth or slightly hairy at 

 the base, the teeth acute but not awned, the 

 dorsal awn absent or, if present, usually straight 

 and not much exceeding the glumes, often pre- 

 sent only on the lower floret, the palea inclosed 

 by the inrolled margin of the lemma, densely 

 short-ciliate on the 2 keels. The florets 

 do not easily disarticulate, a condition 

 probably due to cultivation. Commonly 

 cultivated and often escaped from fields 

 and in the vicinity of elevators, mills, 

 railroads and in waste places, but rarely 

 established permanently. There are sev- 

 FiG. 43. Notholcuslanatus. era! races or possibly species in cultiva- 

 Sf°twoXk?Siset''f=r'o''i tio°- The naked oat (A. mula L.) differs 

 the glumes, X7. in having more than 2 florets and in 



