2l8 



GRAMINEAE. 



VOL. I. 



53. AVENA L. Sp. PI. 79. 1753. 



Annual or perennial grasses, with usually flat leaf-blades and panicled spikelets. Spike- 

 lets 2-many-flowered, or rarely i -flowered; lower flowers perfect, the upper often staminate 

 or imperfect. Scales 4-many (rarely 3) ; the 2 lower empty, somewhat unequal, membranous, 

 persistent; flowering scales deciduous, rounded on the back, acute, generally bearing a dorsal 

 awn, the apex often 2-toothed. Palet narrow, 2-toothed. Stamens 3. Styles short, distinct. 

 Stigmas plumose. Grain oblong, deeply furrowed, enclosed in the scale and palet, free or 

 sometimes adherent to the latter. [Old Latin name for the Oat.] 



About 50 species, widely distributed in temperate regions, chiefly in the Old World. Type 

 species : Avena sativa L. 



Spikelets, exclusive of the awns, 8" long or more ; annuals. 



Flowering scales more or less hispid, the awn with a pronounced spiral column ; rachilla hispid. 



1. A. fatua. 

 Flowering scales glabrous, awnless or with a straight awn slightly spiral at the base. 



2. A. sativa. 

 Spikelets, exclusive of the awns, less than 8" long ; perennials. 



Empty basal scales much shorter than the spikelet ; flowering scales herbaceous, with the awn 



inserted near the apex. 

 Flowering scales with a ring of hairs at the base ; awn equalling or exceeding the scale. 



3. A. Torrcyi. 

 Flowering scales naked at the base ; awn not more than l /> as long as the scale. 



4. A. Smithii. 

 Empty scales, at least the second one, as long as the spikelet or nearly so ; flowering scales scari- 



ous and hyaline above, the awn inserted about the middle. 5. A. Hookeri. 



i. Avena fatua L. Wild Oat. Fig. 526. 



Avena fatua L. Sp. PI. So. 1753. 



Culm i-4 tall, erect, simple, stout, smooth and gla- 

 brous. Sheaths smooth, or scabrous at the summit, 

 sometimes sparingly hirsute, the lower often overlap- 

 ping; ligule i "-2" long; blades 3 '-8' long, i"-4" wide; 

 panicle open, 4'-i2' in length, the branches ascending; 

 spikelets 2-4-flowered, drooping; outer scales f'-i' in 

 length, smooth, enclosing the flowering scales ; flower- 

 ing scales 6"-g" long, with a ring of stiff brown hairs 

 at the base, pubescent with long rigid brown hairs, 

 bearing a long bent and twisted awn. 



In fields and waste places. Ontario and Ohio (according 

 to Hitchcock) and westward to Missouri ; abundant on the 

 Pacific Coast. Naturalized from Europe or Asia. Haver- 

 corn. Poor Oat. Hever. Drake. July-Sept. 



\ 



Avena sterilis L,, a native of Europe, is reported as 

 occurring sparingly as an adventive plant in New Jersey 

 and near Philadelphia, Penn. It can be distinguished 

 from the above by its larger spikelets and longer awns. 



2. Avena sativa L. Oats. Fig. 527. 



Avena sativa L. Sp. PI. 79. 1753. 



A glabrous annual. Culms up to 3 tall; blades 

 flat, up 'to i long and wide, acuminate; panicle 

 4' -9' long, its branches ascending; spikelets, exclusive 

 of the awns, 8"-i2" long, the empty scales broad, 

 acute, the flowering scales glabrous, awnless, or with 

 an imperfect awn which is rarely a little spiral at 

 the base. 



_ Persisting in old fields and as a weed along road- 

 sides and waste places. A native of Europe and Asia. 



