AiEA GRAMINB^ 746 



DE8CEAUPSIA 



sterna Bimple, erect, 6-20 inches high: sheaths usually shorter than the 

 internodes : ligules Jg-l line long: leaves 1-4 inches long, 1-2 lines wide : 

 panicle spike-like, 1-5 inches long, often interrupted below, its branches 

 l}4 inches long or less^ erect: spikelets 2-3- flowered, the empty glumes 

 hispid on the keel, shining, the second about 2^ lines long : flowering 

 glumes 2-2}4 lines_ long, acuminate, scabrous : awn inserted below the 

 sinus, bent and twisted below. In rocky places in the high mountains, 

 California to Alaska and across the continent. 



Yar. molle Gray Man. 641. Stems and leaves minutely soft-downy 

 Range of the type. 



'29 AIRA L. Sp. 6.3. . 



Mostly annual grasses . with narrow leaves and contracted or 

 open panicles. Spikelets small; two-flowered, both flowers perfect, 

 glumes 4, the two lower empty, thin-membranous, acute, subequal, 

 persistent: the flowering glumes usually contiguous, hyaline, mu- 

 cronate or 2-toothed, deciduous, bearing a delicate dorsal awn 

 inserted below the middle. Palet a little shorter than the glume, 

 hyaline, 2-nerved. Stamens 3, with plumose stigmas. Grain en- 

 closed in the glume and palet and often adherent to them. 



A. CAKYOPHYLLEA L. Sp. 66. Hmooth and glabrous throughout : stems 

 6-10 inches high, erect, from an annual root: sheaths mostly basal : ligules 

 1% lines long : leaves 6-25 lines^ long, involute-setaceous : panicle 1-4 

 inches long, open, the branches spreading or ascending : spikelets l-lj^ 

 lines long, the empty glumes acute: flowering glumes very acute, 2-tooth- 

 ed 1 line long: awn 1-2 lines long. Common in dry open places : natural- 

 ized from Europe. 



A. PB^cox L. Sp. 65. Smooth throughout : stems l-r4 inches high, 

 erect, from an annual root, simple, rigid : sheaths shorter than the inter- 

 nodes : ligules about 1}4 lines long : leaves 1 inch long or lessj involute- 

 setaceous : panicle contracted, strict, 6-12 lines long, its base often enclosed 

 in the upper sheath : spikelets about 1)4 lines long, the empty glumes 

 acute : flowering glumes acuminate, 2-tooted at the apes, about 1^ lines 

 long : awn straight, 1-2 lines long. In dry places : naturalized from £u. 



30 DESCHAMPSIA Beauv. Agrost. 91. (1812.) 



Perennial grasses with flat or involute leaves and numerous 

 flowers in contracted or open panicles. Spikelets 2-flowered, 

 both perfect ; the hairy rachella extended beyond the flowers or 

 rarely terminated by a staminate one. 'Glumes 4, rarely more, 

 the 2: lower empty, keeled, acute, membranous shining, persistent ; 

 the flowering glumes of about the same texture, deciduous, 2- 

 toothed at the apex and bearing a dorsal awn. Palet narrow, 2- 

 nerved. Stamens 3. Styles distinct. Stigmas plumose. Grain 

 free, enclosed in the glume. 



D. caespitosa Beauv. Agrost. 160, t. 18, fig. 3. Densely cespitose 

 with very numerous basal leaves: Stems erect, slender 2-4 feet high; sim- 

 ple, glabrous: sheaths much shorter than the internodes: ligules 1-3 lines 

 long : leaves flat 1-1)^ lines wide, smooth beneath, strongly scabrous above, 

 the basal ones j^-}4 ^^ long as the stem, those of the stem 2-6 inches long : 

 panicle open 3-^ inches long, the branches widely spreading or ascending 

 often somewhat flexuous the lower 2-5 inches long : spikelets l?i-2 lines 

 long: empty glumes unequal, lanceolate, acute; flowering glume oblong. 



