GRAMINE.E. (GRASS FAMILY.) 407 



2. A. aristulatUS, Michx. Stem ascending from a decumbent base, 1 to 2 

 feet high : leaves glaucous : spike about 2 inches long, slender and very pale 

 green : outer glumes obtuse, the flowering one slightly exceeding them, its awn 

 attached just below the middle and barely exceeding it. A. geniculatus, var. 

 aristulatus, Torr. From Colorado to California and Oregon, and eastward 

 across the continent. 



13. ARISTIDA, L. TRIPLE-AWNED GRASS. 



Stems generally branching; leaves narrow, often involute; spikelets in 

 simple or panicled racemes or spikes ; grain linear. All grow in sterile, dry 

 soil. 



# Awns unequal, the middle one longer than the lateral ones. 



1. A. basiramea, Engelm. Stems erect, 6 to 15 inches high, slender, 

 much branched at the base, and with short floriferous branches enclosed in the 

 upper leaf sheaths : leaves flat, becoming involute towards the apex, sparsely 

 hairy on the margins below: panicle 1^ to 3 inches long, erect, rather lax, its 

 base sheathed by the upper leaf : glumes linear, unequal, 1-nerved, with a 

 short bristle-like point: flowering glume nearly terete, spotted with black, 

 with a short, acute hairy callus : middle awn about 6 lines long, the lateral 

 ones 4 lines long, spirally twisted below (when mature). Bot. Gazette, ix. 

 76. Minnesota, W. Upham, and ranging through the prairie region of the 

 Northwest. 



* # Awns about equal in length. 



2. A. purpurea, Nutt. Stem simple, erect, slender, 6 to 15 inches high: 

 sheaths scabrous, exceeding the internodes, pilose at the throat: panicle slen- 

 der, 3 to 6 inches long, loosely few-flowered : outer glumes purplish, unequal, 

 bifid and shortly awned : flower densely short-pilose at the pointed base, sca- 

 brous above : awns 1 to 2 lines long, not exceeding the flower, scabrous. Steud. 

 Gram. 134. From Colorado to Texas and westward to the Great Basin. 



Var. longiseta, Vasey. With very long awns. A. longiseta, Steud. 

 Colorado and southward to New Mexico and Texas. 



3. A. oligantha, Michx. Stems tufted, bearing a loosely few-lowered 

 raceme : leaves short : outer glumes nearly equal, the lower ones 3 to 5-nerved, 

 nearly an inch long; awns capillary, 1^ to 3 inches long, much exceeding the 

 slender flower. Colorado and southward, thence eastward to Illinois, Vir- 

 ginia, and the Southern States. 



14. STIPA, L. FEATHER GRASS. 



Perennials, with narrow involute leaves and a loose panicle of early decidu- 

 ous florets. Some of the species are called " Bunch Grass." The flower has 

 a hardened, often sharp-pointed and bearded pedicel or stipe at its base, the 

 callus. 



* Awn for a part of its length distinctly plumose with silky hairs. 



1. S. Mongolica, Turcz. Slender, a foot high, with filiform leaves and 

 a loose few-flowered panicle : glumes membranous, obtuse, about 2 lines long, 

 not quite equal, purplish : flowering glume scarcely shorter, hairy : the bent 

 awn 6 lines in length. Mountains of Colorado. 



