170 



GRAMINEAE. 





2. 



Deschampsia flexuosa (L.) Trin. Wavy Hair-grass. (Fig. 388.) 



Aira flexiiosa L. Sp. PI. 65. 1753. 

 Deschampsia flexuosa Trin. Bull. Acad. Sci. St. 

 Petersb. i: 66. 1836. 



Glabrous throughout, culms i-2^ tall, erect, 

 slender, simple, smooth. Sheaths much shorter 

 than the internodes; ligule i" long or less;, 

 leaves involute-setaceous, smooth beneath, scab- 

 rous above, the basal very numerous, one-fifth 

 the length of the culm or less, those of the culm, 

 i '-3' long; panicle open, 2 / -8 / in length, the 

 branches ascending or erect, sometimes widely 

 speading, naked at the base, flexuous, the lower 

 i>'-5' long; spikelets 2X // -2> // long; flow- 

 ering scales about 2" long, acutely toothed at 

 the apex; awns bent and twisted, much ex- 

 ceeding the scale; upper scale reaching to or 

 extending beyond the apices of the empty ones. 



In dry soil, Greenland and Newfoundland to On- 

 tario and Michigan, south to North Carolina and 

 Tennessee. Ascends to 5100 ft. in the Adirondacks. 

 Also in Europe. July-Aug. 





3. Deschampsia atropurpurea (Wahl.) Scheele. Mountain Hair-grass. 



(Fig. 389.) 



Aira atropurpurea Wahl. Fl. Lapp. 37. 1812. 

 Deschampsia atropurpurea Scheele, Flora, 27: 56. 

 1844- 



Glabrous and smooth or very nearly so, culms 

 6'-i8 / tall, erect, simple, rigid. Sheaths shorter 

 than the internodes; ligule i" long or less, trun- 

 cate; leaves i // -2 // wide, erect, sometimes slightly 

 scabrous above, the basal 2^ / -5 / long, those of the 

 culm shorter; panicle contracted, usually purple or 

 purplish, i / -2 / in length, the branches erect, or 

 sometimes ascending, the lower J^'-i^' long; 

 spikelets 2>" long; flowering scales about i^" 

 long, erose-truncate at the apex; awns bent and 

 much .longer than the scales; upper scale much 

 exceeded by the very acute outer ones. 



On alpine summits of New York, New England, 

 Montana, Oregon and Washington, north to Labrador 

 and Alaska. Also in Europe. July- Aug. 



43. TRISETUM Pers. Syn. i: 97. 1805. 



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

 lets 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 flow- 

 ering scales in some species.] 



About 50 species, widely distributed in temperate or mountainous regions. Besides the follow- 

 ing, about 8 others occur in the western parts of North America. 



Flowering scales all bearing long dorsal awns. 



Panicle contracted, dense; flowering scales 2J4" long or less. i. T. subspicatum. 



Panicle open, loose; flowering scales 2'A" long or more. 2. T. flavescens. 



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



3. T. Pennsylvanicum. 



