618 GRAMINE^E. (GRASS FAMILY.) 



stout (l£°-3° high) ; panicle contracted; pakts linear, f- 1' long (including the 

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

 greenish glumes ; the twisted strong awn (3^'- 7' long, pubescent below, rough 

 above. (S. juncca, 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; 

 the 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 late. 



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

 -t- Awns very unequal ; the much shorter or minute lateral ones erect ; the elongated 

 middle one horizontal or turned downwards : glumes equal or the upper one longer : 

 low (5'- 18' high) and branching, mostly t ujted annuals. 



** Spikelets Jew in loose simple spikes or racemes : glumes 3 - 5-nerved. 



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 (Engelmann, Vasey) and Kentucky (Michaux). 

 — Var. uniaristata, with lateral awns wanting. Ringwood, Illinois, Vasey. 



++ ++ Spikelets more numerous : glumes (3" -4" long) carina tely \-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 rejlexed 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 awns 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. 



•*- -i- 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 ^.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. 



