618 GRAMINE^. (grass FAMILY.) 



Stout (UO-3° hijrh) ; panicle contracted; pakis linear, 5'-l' lon;^ (including the 

 long callus), pubescent below, shorter than the lanceolate slender subulate-pointed 

 greenish y/u/Hf-s; the twisted strong awn (3^' -7' long, pubescent below, rough 

 above. (S. juncea, Pursh ?) — Plains and prairies, from Illinois and N. Michi- 

 gan northwestward. May -July. 



16. ARiSTIDA, L. Tkiple-awxed Gkas.s. (PI. 8.) 



Glumes unequal, often brittle-pointed. Lower palct tipped with three awns; 

 the upper much smaller. Otherwise much as in Stip.1. — Culms branching: 

 leaves narrow, often involute. 8j)ikelets in simple or paniclcd racemes or spikes. 

 Grain linear. (Name from arista, a beard or awn.) All grow in sterile, dry 

 soil, and all ours have the awns naked and persistent, and flower late. 



* Aw/is separate to the base, not jointed ivith the palet. 

 ••- Axvns very uncf/iiid ; the much shorter or minute lateral ones erect; the elonqated 

 middle one horizontal or turned dowmvards : rjluines equal or the upper one longer: 

 low (5'- 18' hiffh) and branchinr/, mostli/ tufled annuals. 



■*-*■ Sj'Ikcltts few in hose simple spilccs or racemrs: (/liimes S-H-neri'ed. 



1. A. ramosissima, Engelm. mss. Culms diffusely much branched; 

 glumes (9" -10" long) rather shorter than the flower; middle awn 1' long, 

 soon abruptly hooked-recurved, the lateral ones hardly 2" long ; ligule truncate, 

 bearded. — Dry prairies of Illinois {Enf/elmann, Vasei/) and Kentucky (Michaux). 

 — Var. UNIARI8TATA, Avith lateral awns wanting. Odin, S. Illinois, Vasey. 



■M. ++ Spikehts more numerous : rjlumes (.3"-4" long) carinately l-nerved. 



2. A. dichotoma, Michx. (Poverty Gkas.s.) Culms low, much 

 branched throughout, ascending; spikelets in short narrow clusters; glumes 

 nearly equal, longer than the flower, fully equalling its minute lateral awns, the 

 soon reflexfd middle awn about the length of the })alet. — Dry, sandy or gravelly 

 fields: common, especially southward. 



3. A. gracilis, Ell. Culms slender, erect (6'- is' high), naked above and 

 terminating in a shmder raceme- or spike-like virgate panicle ; glumes about 

 the length of the flower, the exserted lateral awns i-arying from one third to fully 

 half the length of the horizontally bent middle one; or in var. ijepaupek.\ta, from 

 one fifth to one third its length. — Sandy soil, coast of Mass. and from Illi- 

 nois southward. — Middle awn 6" -9" long, in the ordinary forms. In the var. 

 which abounds on micaceous hills near Philadelphia (C E. Smith), the flowers 

 are much smaller, and awns shorter; but it passes into the larger form. 



H- -1- Awns all divei-ging and alike, or the lateral ones moderately shorter. 

 ++ Glumes equal or the upp^r one longer. 



4. A. Strieta, Michx. Culms (2° -3° high) densely tufted from a /lerennmi 

 root, bearing a (1°) long spiked panicle ; leaves involutc-thread-form, long, rigid, 

 sometimes downy: awns about the length of the flower (0") or the lateral one 

 third shorter. — Virginia and southward. 



5. A. oligantha, Michx. Culms (G"- 20" high) tufted from an annual? 

 root, bearing a loosely few flowered raceme ; leaves short, somewhat involute when 

 dry; lower glume 3-.5-nQi-ved (nearly 1' long); awns capillary, l^'-3' long, 

 much exceeding the slender flower. — Virginia to Illinois, and common south- 

 westward. 



