288 MISC. PUBLICATION 200, U. S. DEPT. OF AGRICULTURE 



55. DESCHAMPSIA Beauv. Hairgrass 



Spikelets 2-flowered, disarticulating above the glumes and between 

 the florets, the hairy rachilla prolonged beyond the upper floret as a 

 stipe, this sometimes bearing a reduced floret; glumes about equal, 

 acute or acutish, membranaceous; lemmas thin, truncate and 2- to 4- 

 toothed at summit, bearded at base, bearing a slender awn from or 

 below the middle, the awn straight, bent or 

 twisted. Low or moderately tall annuals or 

 usually perennials, with shining pale or purplish 

 spikelets in narrow or open panicles. Standard 

 species, Deschampsia caespitosa. Included in 

 Aira by some authors. Named for Deschamps. 

 Deschampsia caespitosa is often the domi- 

 figure 567.— Distribution of nant grass in mountain meadows, where it 



Trisetum internum. fumishes exce llent forage. 



Plants annual; foliage very scant 1. D. danthonioides. 



Plants perennial; foliage not scant, one- third to half the entire length of the 

 culm. 

 Panicle narrow, the distant branches appressed. Blades filiform, lax. 



2. D. ELONGATA. 



Panicle open or contracted, if narrow, not more than one-fourth the length of 



the culm. 



Blades thin, flat; glumes exceeding the florets 3. D. atropurpurea. 



Blades firm or filiform; glumes not exceeding the upper floret. 



Blades filiform, flexuous; awn exserted, geniculate, twisted. 



4. D. FLrEXTOSA. 



Blades flat or folded, stiff; awn included or slightly exserted, straight. 



Panicle open, usually nodding or drooping 5. D. caespitosa. 



Panicle narrow, condensed, erect 6. D. holciformis. 



1. Deschampsia danthonioides (Trin.) Munro. Annual hair- 

 grass. (Fig. 568.) Annual; culms slender, erect, 15 to 60 cm tall; 

 blades few, short, narrow; panicle open, 7 to 25 cm long, the capillary 

 branches commonly in twos, stiffly ascending, naked below, bearing a 

 few short-pediceled spikelets toward the ends; glumes 4 to 8 mm long, 

 3-nerved, acuminate, smooth except the keel, exceeding the florets; 

 lemmas smooth and shining, somewhat indurate, 2 to 3 mm long, the 

 base of the florets and the rachilla pilose, the awns geniculate, 4 to 6 

 mm long. © — Open ground, Alaska to Montana and Baja 

 California; Texas (Buckley, but the locality possibly erroneous); also 

 Chile (fig. 569). Variable in the size of the spikelets. A form 

 described from southern California as D. gracilis Vasey, with some- 

 what laxer panicles, the rather more numerous spikelets only 4 to 5 

 mm long, grades into the usual form. 



2. Deschampsia elongata (Hook.) Munro. Slender hairgrass. 

 (Fig. 570.) Culms densely tufted, slender, erect, 30 to 120 cm tall; 

 blades soft, 1 to 1.5 mm wide, flat or folded, those of the basal tuft 

 filiform; panicle narrow, as much as 30 cm long, the capillary branches 

 appressed; spikelets on short appressed pedicels; glumes 4 to 6 mm 

 long, 3-nerved, equaling or slightly exceeding the florets; lemmas 2 

 to 3 mm long, similar to those of D. danthonioides, the awns shorter, 

 straight. % — Open ground, Alaska to Wyoming, south to Arizona 

 and California; Mexico (fig. 571) ; Chile. 



3. Deschampsia atropurpurea (Wahl.) Scheele. Mountain hair- 

 grass. (Fig. 572.) Culms loosely tufted, erect, purplish at base, 

 40 to 80 cm tall; blades flat, rather soft, ascending or appressed, 

 5 to 10 cm long, 4 to 6 mm wide, acute or abruptly acuminate; 



