118 POACEAE 
19. Aristida gracilis Ell. Stems densely tufted, 1.5-6 dm. tall, slender, finally 
more or less branched : leaf-sheaths equalling or shorter than the internodes, glabrous, 
or the lower ones sparingly pubescent ; blades 3-12 cm. long, 1 mm. wide or less, erect, 
flat: panicle 5-15 em. long, its short branches appressed : spikelets 5-7 mm. long, the 
2 outer scales 1-nerved, usually awn-pointed, the first equalling or a little shorter than the 
second, sparingly hispidulous, the flowering scale 5-6 mm. long, frequently barred or 
spotted with black, more or less hispidulous, especially on the keel, the central awn 
spreading, 6-10 mm. long, rarely longer, the lateral awns erect, 1-3 mm. long, occasion- 
ally longer. 
In dry soil, Vermont to Illinois, Kansas, Florida and Texas. Summer and fall. 
20. Aristida intermèdia Scribo. & Ball. Stems slender, finally branching, 3-8 
dm. tall: leaf-sheaths glabrous or sparsely hirsute ; blades 5-15 cm. long, 2 mm. wide or 
less, erect, involute : panicle 2-4 dm. long, slender, its branches appressed : spikelets 8-10 
mm. long, the empty scales manifestly awned, about equal, the flowering scale strongly his- 
pidulous above the middle, equalling or exceeding the empty scales, the awns spreading, 
the middle one 15-25 mm. long, the lateral ones shorter. 
In sandy soil, Iowa to Mississippi and Texas. Summer and fall. 
21. Aristida Chapmaniàna Nash. Stems densely tufted, 7-10 dm. tall, finally more 
or less branched : leaf-blades 1-2 dm. long, 1.5-2.5 mm. broad, flat, long-acuminate : panicle 
2-4 dm. long, the branches short and appressed : spikelets 6-8 mm. long, rather crowded 
on the branches, the 2 outer scales 1-nerved, or the first rarely with faint lateral nerves, 
the first one shorter than the second, usually strongly hispidulous, the flowering scale about 
5 mm. long, glabrous or sparingly hispidulous on the upper part of the keel, the central awn 
widely spreading, at right angles to the scale, 1.8-2.5 cm. long, the lateral awns erect, 
usually a little more than 3 as long as the central awn, rarely shorter. 
In dry sandy soil, North Carolina to Florida and Mississippi. Fall. 
22. Aristida purpurascens Poir. Stems tufted, 3-8 dm. tall, usually simple, or 
occasionally branched : leaf-sheaths smooth and glabrous, or the lower ones sometimes 
ubescent ; blades 0.5-2 dm. long, 1-2 mm. wide, flat, long-acuminate: panicle 1.5-3 dm. 
ong, its branches appressed and usually short: spikelets 9-12 mm. long, rarely a little 
smaller, usually crowded, the 2 outer scales 1-nerved, sometimes awn-pointed, the first 
one usually exceeding the second, occasionally equalling it, hispidulous, the flower- 
ing scale 6-8 mm. long, glabrous or sparingly hispidulous, the awns more or less spreading, 
especially the central one which is 1.5-2.5 cm. long, the lateral awns from 2 as long to 
nearly equalling it. 
In dry soil, Massachusetts to Minnesota, Florida and Texas. Fall. 
23. Aristida palüstris (Chapm.) Vasey. Stems densely tufted, 8-12 dm. tall, firm 
and hard at the base: leaf-blades 2-4 dm. long, 2-3 mm. wide: panicle 2-5 dm. long, its 
branches closely appressed, the longer 5-7 cm. long: spikelets 10-12 mm. long, the first 
scale prominently 2—3-nerved, strongly hispidulous, from a little shorter than to slightly 
exceeding the second, the flowering scale 8-9 mm. long, smooth and glabrous, the callus 
fully 1 mm. long, sparsely pilose, the central awn widely spreading, 1.5-3 cm. long, the 
lateral awns erect or nearly so, from $ as long as to nearly equalling it. 
In swamps and wet places, Florida to Louisiana. Late summer and fall. 
24. Aristida lanósa Muhl. Stems 8-14 dm. tall, simple, rather stout : leaf-sheaths 
confined to the lower part of the stem, densely woolly pubescent ; blades 3-5 dm. long, 2-7 
mm. wide, flat: panicle 4-6 dm. long, its axis villous at the nodes, its lower branches dis- 
tant, ascending, 8-12 cm. long: spikelets 12-17 mm. long, the 2 outer scales 1-nerved, the 
first much exceeding the second, the flowering scale 8-10 mm. long, the central awn widely 
spreading, 1.5-2.5 cm. long, the lateral awns erect or ascending, about å as long. 
In dry thickets, Delaware to Florida, and Texas. Fall. 
25. Aristida spiciformis Ell. Stems tufted, 4-10 dm. tall, simple: leaf-sheaths 
overlapping on the lower part of the stem ; blades 1-3 dm. long, flat, or involute when dry, 
3-5 mm. wide: panicle 12-20 cm. long, oblong, very dense: spikelets densely crowded, 
the 2 outer scales 1-nerved, the first scale about À as long as the second which is about 
1 cm. long, the former with an awn longer than its body, the latter bearing an awn 0 
about equal length, the flowering scale, exclusive of the awns and including the 2 mm. long 
callus, about 6 mm. long, the awns united below into a twisted flexuous column 1.5-2.5 cm. 
long, the free portion of the awns spreading or ascending, the central awn 2.5-3.5 cm. long, 
the lateral ones a little shorter. 
In moist or flat pine lands, South Carolina to Florida. Summer and fall. 
26. Aristida pátula Chapm. Stems tufted, 1-1.5 m. tall, simple, the leaves confined 
to the lower part of the stem: leaf-sheaths overlapping, smooth, usually with a pubescent 
