2l6 



GRAMINEAE. 



VOL. I. 



2. Deschampsia flexuosa (L.) Trin. Wavy Hair-grass. Fig. 521. 



Aira fle.ruosa L. Sp. PI. 65. 1753. 



Deschampsia fle.ruosa 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; blades 

 involute-setaceous, smooth beneath, scabrous 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 ascend- 

 ing or erect, sometimes widely spreading, naked at 

 the base, flexuous, the lower ii'-5' long; spikelets 

 2\"-2\" long ; flowering scales about 2" long, 

 acutely toothed at the apex ; awns bent and twisted, 

 much exceeding the scale ; upper scale reaching to 

 or extending beyond the apices of the empty ones. 



In dry soil, Greenland and Newfoundland to On- 

 tario, south to North Carolina and Tennessee. As- 

 cends to 5100 ft. in the Adirondacks. Also in Europe. 

 Wood Hair-grass. July-Aug. 



3. Deschampsia atropurpurea (Wahl.) Scheele. Mountain Hair-grass. Fig. 522. 



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

 D. 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, truncate; 

 blades i"-2" wide, erect, sometimes slightly scabrous 

 above, the basal z4'-5' long, those of the culm 

 shorter; panicle contracted, usually purple or pur- 

 plish, i '-2' in length, the branches erect, or some- 

 times ascending, the lower -il' long; spikelets 2\" 

 long; flowering scales about \\" 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, from New England to Colorado 

 and Oregon, north to Labrador and Alaska. Also in 

 Europe. July-Aug. 



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



Mostly perennial tufted grasses, with flat leaf-blades 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 flow- 

 ering scales in some species.] 



About 60 species, widely distributed in temperate or mountainous regions. Besides the follow- 

 ing, about 8 others occur in the western parts of North America. Type species : Avena striata Lam. 



Flowering scales all bearing long dorsal awns. 



Panicle contracted, dense; flowering scales 2^/2" long or less. i. T. spicatum. 



Panicle open, loose; flowering scales 2 l / 2 " long or more. 2. T. flavesccns. 



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



3. T. pennsylvanicum. 



