GRAMINEAE. 117 



summits of N. Y.. N. E., Mont., Ore. and Wash., north to Lab. and Alaska. Also 

 in Europe. July-Aug. 



49. TRISETUM Pers. 



Mostly perennial tufted grasses, with flat leaves and spike-like or open panicles. 

 Spikelets 2-4-flowered, the flowers all perfect, or the uppermost staminate; rachilla 

 glabrous or pilose, extended beyond the flowers. Scales 4-6, membranous, the 2 

 lower empty, unequal, acute, persistent; flowering scales usually shorter than the 

 empty ones, deciduous, 2 -toothed, bearing a dorsal awn below the apex, or the 

 lower one sometimes awnless. Palet narrow, hyaline, 2-toothed. Stamens 3. Styles 

 distinct. Stigmas plumose. Grain free, enclosed in the scale. [Latin, referring 

 to the three bristles (one awn and two sharp teeth) of the flowering scales in some 

 species. ] About 50 species, widely distributed in temperate or mountainous regions. 

 Besides the following, about 8 others occur in the western parts of N. Am. 



Flowering scales all bearing long dorsal awns. 



Panicle contracted, dense ; flowering scales 5 mm. long or less. 



i. T. subspicatum. 



Panicle open, loose; flowering scales 5 mm. long or more. 2. T. flavescens. 

 Lower flowering scale not bearing a long dorsal awn, a rudiment sometimes present. 



3. 7'. Pennsylvam'cum. 



1. Trisetum suspicatum (L.)Beauv. NARROW FALSE-OAT. (I. F. f. 390.) 

 Softly pubescent or glabrous. Culms 1.5-6 dm. tall, erect, simple ; leaves 2.5-10 

 cm. long, 1-4 mm. wide; panicle spike-like, 2.5-12.5 cm. in length, often inter- 

 rupted below, its branches 3.75 cm. or less long, erect; spikelets 2-3-flowered, the 

 empty scales hispid on the keel, shining, the second about 5 mm. long, the first 

 shorter; flowering scales 4-5 mm. long, acuminate, scabrous, each bearing a long 

 bent and somewhat twisted awn. In rocky places, Lab. to Alaska, south on the 

 mountains to N. Car., N. Mex. and Cal. Also in Europe and Asia. Aug. -Sept. 



2. Trisetum flavescens (L.)R. & S. YELLOW FALSE-OAT. (I. F. f. 391.) 

 Culms 4.5-7.5 dm. tall, erect, simple, smooth, glabrous. Sheaths more or less pubes- 

 cent; leaves 3. 75-12. 5 cm. long, 2-6 mm. wide, scabrous, sometimes sparingly hairy; 

 panicle open, 5-12.5 cm. in length, the branches ascending or erect, somewhat flex- 

 uous, naked below, the lower 2 5-5 cm. long; spikelets 3~4-flowered ; empty scales 

 smooth and glabrous, the second acute, 5 mm. long, the first about half as long, 

 narrower, acuminate; flowering scales 5-6 mm. long, scabrous, bearing a long bent 

 and twisted awn. Introduced into Mo. and Kans. Native of Europe and Asia. 

 Panicle yellow, turning dull brown. July-Aug. 



3. Trisetum Pennsylvanicum (L.) Beauv. MARSH FALSE-OAT. (I. F. f. 

 392.) Culms 3-9 dm. tall, erect, simple, slender and often weak, smooth and gla- 

 brous. Sheaths shorter than the internodes, sometimes scabrous; leaves 2.5-15 

 cm. long, 2-6 mm. wide, rough; panicle 520 cm. in length, yellowish, narrow, 

 the branches ascending, the lower 2.5-5 cm - l n g> spikelets 2-flowered; outer scales 

 smooth, shining, subequal, the second 4-5 mm. long; flowering scales 4-5 mm. 

 long, scabrous, the lower not long-awned, but a rudimentary awn sometimes pres- 

 ent, the upper with a long bent and twisted awn. In swamps and wet meadows, 

 N. Y. to III., south to Fla. and La. Ascends to 1050 m. in Va. Panicle sometimes 

 loose and nodding. June-July. 



50. A VENA L. 



Annual or perennial grasses, with usually flat leaves and panicled spikelets. 

 Spikelets 2-many-flowered, or rarely i-flowered; lower flowers perfect, the upper 

 often staminate or imperfect. Scales 4-many (rarely 3); the two 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 adher- 

 ent to the latter. [Old Latin name for the oat.] About 50 species, widely dis- 

 tributed in temperate regions, chiefly in the Old World. Oats (Avena sativa L.) 

 sometimes appear in waste places or in fields where it has been cultivated. 



