618 gramine^e. (grass family.) 



stout (l|°-3° high) ; panicle contracted; palets linear, %' -V long (including the 

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

 greenish glumes; tbe 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. Triple-awned Grass. (PI. 8.) 



Glumes unequal, often bristle-pointed. Lower palet tipped with three awns ; 

 tbe upper much smaller. Otherwise much as in Stipa. — Culms branching: 

 leaves narrow, often involute. Spikelets in simple or panicled 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 lata. 



* Awns separate to the base, not jointed with the palet. 

 ■»- Awns veryuneqwd; the much shorter or minute lateral ones erect; the elongated 

 middle one horizontal, or turned downward* : glumes equal or the upper one longer: 

 low (5'- 18' high) and branching, mostly tufted annuals. 



■«■+ Spikelets few in loose simple spikes or racemes: glumes 3 - 5-nerved. 



1. A. ramosissinia, 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 (Engelmann, Vasty) and Kentucky (Michaux). 

 — Var. uniaristata, with lateral awns wanting. Odin, S. Illinois, Vasey. 



*+ ++ Spikelets more numerous : glumes (3" -4" long) carinately l-nerved. 



2. A. dichotoma, Michx. (Poverty Grass.) 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 reflwed middle awn about the length of the palet. — Dry, sandy or gravelly 

 fields : common, especially southward. 



3. A. gracilis, Ell. Culms slender, erect (6'- 18' high), naked above and 

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

 the length of the flower, the exserted lateral axons varying from one third to fully 

 half the length of the horizontally bent middle one; or in var. depauperata, 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. 



•*- *r Awns all diverging and alike, or the lateral ones moderately shorter. 

 ++ Glumes equal or the upper one longer. 



4. A. Stricta, Michx. Culms (2° -3° high) densely tufted from a perennial 

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

 sometimes downy: awns about the length of the flower (6'') or the lateral one 

 third shorter. — Virginia and southward. 



5. A. oligantha, Michx. Culms (6' -20' high) tufted from an annual? 

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

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

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

 westward. 



