POACEAE EEE 
ll. Aristida purpurea Nutt. Stems tufted, 2-4 dm. tall, slender, simple, leafy : 
leaf-blades involute, at least when dry, often curved, those on the stem 2-5, 4-12 cm. 
long: panicle 1-2 dm. long, its branches spreading or ascending, filiform, flexuous, often 
with a long naked base: spikelets 12-15 mm. long, the 2 outer scales 1-nerved, frequently 
awned, the first about } as long as the second, the flowering scale about 1 cm. long, a little 
shorter than the second scale, the awns ascending, the central one about 3-5 cm. long, 
the lateral awns a little shorter. 
In dry sandy soil, Arkansas and Louisiana, to New Mexico. Spring and summer. 
12. Aristida micrantha (Vasey) Nash. Stems tufted, 2-4 dm. tall, slender, simple : 
leaf-blades 4-15 cm. long, involute, at least when dry : panicle 8-12 em. long, its branches 
filiform, flexuous, spreading or ascending: spikelets 2-4 on the longer branches, the 2 
outer scales 1-nerved, the second one 8-10 mm. long, the flowering scale 6-8 mm. long, the 
awns ascending or nearly erect, the central awn 1.5-2 cm. long, rarely longer, the lateral 
awns a little shorter. 
In dry soil, Texas. Summer. 
13. Aristida longiséta Steud. Stems tufted, 2-4 dm. tall, simple : leaf-blades 3-10 
em. long, involute, at least when dry : panicle 1-2 dm. long, its branches usually ascend- 
ing, bearing generally 1 spikelet, or in the longer branches sometimes 2 spikelets : spike- 
lets 2-2.5 cm. long, the 2 outer scales 1-nerved, the first one about 4 as long as the second, 
the flowering scale 12-16 mm. long, occasionally a little shorter, from a little over 3 3 as 
long as the second scale, the awns ascending, the central one 6-11 em. long, the lateral ones 
equalling it or a little shorter. 
In dry sandy soil, Montana and Washington to Nebraska, Texas and Mexico. Summer and fall. 
14. Aristida gyrans Chapm. Stems 3-4 dm. tall, slender, simple: leaf-blades 
6-12 cm. long, involute, about 0.5 mm. in diameter: panicle about 12 cm. long, slender, 
its few branches short and appressed : spikelets 10-11 mm. long, the 2 outer scales 1-nerved, 
the first one shorter than the second, the flowering scale about 6 mm. long, including the 
1.5 mm. long callus, the apex a little twisted, the awns ascending, loosely twisted together 
at the base, the central awn about 12 mm. long, the lateral ones a little shorter. 
In sand, Keys of Caximbas Bay, southern Florida; also in Cuba. Summer and fall. 
15. Aristida Reverchónii Vasey. Stems tufted, 2-4 dm. tall, simple: leaf-blades 
2-12 cm. long, involute, about 0.5 mm. in diameter: panicle 1-1.5 dm. long, its branches 
usually short and appressed, rarely long and somewhat spreading: spikelets on short pedi- 
cels, the 2 outer scales 1-nerved, the first one much shorter than the second which is 8-10 
mm. long, the flowering scale 9-11 mm. long, usually hispidulous, with a long slender 
more or less twisted summit, a little exceeding the second scale, the awns ascending, the 
central one 1.5-2.5 cm. long, the lateral ones a little shorter. 
In dry soil, the Indian Territory and Texas. Spring and summer. 
16. Aristida oligántha Michx. Stems tufted, 2-6 dm. tall, branching: leaf-sheaths 
shorter than the internodes, smooth and glabrous ; blades 0.5-2 dm. long, 1-2 mm. wide: 
aniele 1-2 dm. long, simple, its branches very short and bearing a single spreading spike- 
et: spikelets 2-3 cm. long, the 2 outer scales usually awned, the first 5-7-nerved, from a 
little shorter than the second to a little exceeding it, 1.5-2 cm. long, the awns ascending, 
the central one 3.5-7 cm. long, the lateral ones a little shorter. 
In dry usually sterile soil, New Jersey to Nebraska, Mississippi and Texas. Summer and fall. 
17. Aristida stricta Michx. Stems densely tufted, 5-10 dm. tall, simple: leaf- 
sheaths, the lower ones and especially those on the innovations, villous at the apex ; blades 
involute, even when fresh, 0.5-3 dm. long, about 0.7 mm. in diameter, the lower ones and 
those on the innovations densely villous at the base: panicle 1-3 dm. long, the short ap- 
pressed branches in alternate fascicles of 2 or 3: spikelets 10-11 mm. long, the 2 outer 
scales 1-nerved, usually awn-pointed, the first shorter than the second, the flowering scale 
7-9 mm. long, glabrous or sparingly hispidulous toward the summit, the awns more or less 
spreading, the central one 11-17 mm. long, the lateral ones from # to nearly as long. 
In dry sandy soil, Virginia (according to S. Watson) to Florida. Spring to fall. 
18. Aristida condensàta Chapm. Stems single or few in a cluster, 6-10 dm. tall, 
simple : leaf-sheaths confined to the lower part of the stem, overlapping, glabrous.or spar- 
ingly pubescent ; blades 2-3 dm. long, flat when fresh, 2-3 mm. wide at the base from 
which they gradually taper to a long slender acumination : panicles 2-5.5 dm. long, usually 
densely spikelet-bearing, its branches erect or nearly so, the longer from 3-13 dm. long, 
the spikelets erowded and overlapping: spikelets 8.5-10 mm. long, the 2 outer scales 
l-nerved, glabrous, the first equalling or very little shorter than the second, the flowering 
scale about 7 mm. long including the 1 mm. long and densely pilose callus, glabrous, the 
awns spreading, the central one 10-14 mm. long, the lateral ones from $ as long as to 
nearly equalling it. [A. Combsii Scribn. & Ball. ] 
In dry sandy soil, Florida. Fall. 
