640 GRAMINE^. (grass FAMILY.) 



row, often involute. Spikelets in simple or panic-led racemes or spikes. Grain 

 linear. All grow in sterile, dry soil, and all ours have the awns naked and 

 persistent, and flower late. (Name from arista, a beard or awn.) 

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



~ Axons very unequal ; the much shorter or minute lateral ones erect, the elongated 

 middle one horizontal or turned downward ; low (5-18' high) and branch 

 ing, mostly tufted annuals, and the spikelets in nearly simple spikes. 

 •*■*■ Middle awn more or less coiled. 



1. A. ramosissima, Engelm. Culms much branched; spikes loose, 

 osually exserted ; lower glumes 6-10" long, exceeding the upper, usually 

 rather strongly 3-5-nerved; middle awn 1' long, soon abruptly hooked-re- 

 curved, the lateral ones 1-3" long. — Dry prairies of 111., Ky., and Mo. ^^ 

 Also var. uxiaristXta, Engelm., with the lateral awns wanting. 



2. A. basiramea, Engelm. Spikes closer, mostly enclosed at base, at 

 all the lower nodes (even to the base of the culm) very short and sessile ; lower 

 glumes 4 - 8" long, mostly thin and 1-nerved or rather faintly 3-nerved ; middle 

 awn very slender, 6" long, the lateral 2" long. — 111. to Neb. and Minn. 



3. A. dichotoma, Michx. (Poverty Grass.) Culms low, very slen- 

 der, much branched throughout, ascending ; spikelets in narrow strict simple 

 or compound spikes; lower glumes nearly equal (3-4'' long), longer than the 

 flowering glume and fully equalling its minute lateral awns (or unequal and 

 shorter, in var. CuRxfssii, Gray), the soon reflexed middle awai about as long. 

 — Dry, sandy or gravelly fields; common, Maine to 111., and southward. 



•*-*■ •*-*■ Middle awn nearly straight (not coiled). 



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

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

 1-nerved, about the length of the upper, the exserted lateral awns varying from 

 one third to fully half the length of the horizontally bent middle one : or in 

 var. depauperXta, from one fifth to one third its length. — Sandy soil, coast 

 of ]Mass., and from 111. southward. — Middle awn 3 - 9" long in the ordinary 

 forms, but not rarely shorter, and very variable often on the same plant. 



t- "f Awns all diverging and alike, or the lateral ones moderately shorter, rarely 



at all coiled. 



HH. Glumes equal or the middle one longer. 



5. A. Strlcta, Michx. Culms (2-3° high) densely tufted from a peren 

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

 rigid, sometimes downy; awns about the length of the glumes (6") or the lat- 

 eral one third shorter. — Ya. and southward. 



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

 root, bearing a loosely fev:-flowered raceme ; leaA'es short, somewhat involata 

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

 long, much exceeding the slender spikelet. — Va. to 111., and common south- 

 westward. 



7. A. purpurea, Nutt. Perennial ; culms (1° high or less) densely tufted, 

 spreading; leaves revolute and filiform, short; panicle loose, of rather few 

 slender-pedicellate spikelets; lower glumes thin, 1-nerved, loose, the outer 



