GR AMINES. (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-J 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, Xutt. 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 Xew Mexico and Texas. 



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

 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 

 nwn 6 lines in length. — Mountains of Colorado. 



