550 GRAMINK.E. (GRASS FAMILT.) 



15. A It 1ST I DA, L. TRIPIE- IWNED GRASS. 



Glumes unequal, often bristle-pointed. Lower palea tipped with three awns *, 

 the upper palea much smaller. Otherwise much as in Stipa. Culms branch- 

 ing : leaves narrow, often involute. Spikclcts in simple or panicled racemes 

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

 Boil, and all ours have the awns naked and persistent, and flower towards tho 

 end of summer. 



* Awns separate to the base, not jointed icith the palea. 



- Awn very unequal; the 2 -lateral merely short erect bristles, scarcely \ or \ the 

 length of the horizontal at length recurved middle one : root annual : culms tufted, 

 much branched throughout, low (5'- 18' high} : racemes short and spike-like. 



1. A. <licli6tOBlia, Michx. (POVERTY GRASS.) Culms erect or ascend- 

 ing; spikelets small, mostly crowded and panicled; glumes \-nerred, ^'-J long, 

 exceeding the flower, which bears a middle awn of about its own length. Com- 

 mon in old fields, &c., especially southward. 



2. A ramosissima, Engelm. mss. Culms diffuse ; spiked raceme sim- 

 ple and loosely flowered; glumes $'-$' long, 3 - 5-nerved, aboat equalling the 

 flower, the soon recurved middle awn 1' long. Dry prairies of Illinois (Engel- 

 mann), and Kentucky (herb. Michaux). Glumes short-awned ; the lower 4 -5- 

 nerved; the inner and longer one 3-nerved, 2-cleft at the tip. Lateral awns of 

 the palea only l" - 2" long. Ligule truncate, bearded. 



- - Awns unequal but similar ; the 2 lateral about half the length of the horizontally 

 bent middle one : root annual: culms branched only towards the base, naked above, 

 bearing a long and slender spiked raceme or virgate panicle. 



3. A. griicilis, Ell. Culms slender, erect (6' -18' high); flower as long 

 as the glumes (2" -3" long) ; lateral awns as long as the palea, the middle one 

 '-' long. Sand, E. Massachusetts and New Jersey to Illinois, and south- 

 ward. 



--- Awns nearly equal, divergently spreading : root perennial. 



++ Culms simple or nearly so (l-2 high), terminated by a long and strict virgate 



many-flowered spiked panicle from 6' to 18' in length. 



4. A. Stricta, Michx. Leaves soon involute-filiform, rigid, dou-ny or gla- 

 brous ; lower palea smooth, 3" -4" long, the equally spreading awns long, or 

 .he lateral rather shorter. Virginia and southward. 



5. A. purpliraSCCns, Poir. Lcnrcs glabrous, less rigid ; lower palea 

 rough or minutely serrulate-hispid on the keel and 'he slender lateral nerves, 

 4"- 5" long; the divaricate middle awn 1' long, the lateral a little shorter and 

 at first erect. (A. racemosa, Muhl. A. Geyeriana, Staid.) Massachusetts to 

 Michigan, Illinois, and southward ; common. 



-* ** Culms branching bcloir (1- H high), the branch*'* naked above an 1 r.icemosdy 

 or panicitlately several- (4 - 12-) flowered* 



6. A. oligrtiitlia, Michx. Spikelets large, very short-pcdicolled ; glumes 

 equalling the flower, 8"- 10" long, the lower 3-5-nerved and 2-cleft at the lip, 

 the upper 1 -nerved and more awned at the tip ; awns of the palea !' -3' long, 



