550 GRAMINKJE. (GRASS FAMTLT.) 



15. ARISTIDA, L. TRIPI E-AWNED 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. Spikelcts in simple or panicled racemes 

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

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

 end of summer. 



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



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

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

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



1. A. dicli6toma, Michx. (POVERTY GRASS.) Culms erect or ascend- 

 ing; spikelets small, mostly crowded and panicled ; glumes \-nerved, y - 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, about equalling the 

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

 mann), and Kentucky (Jterb. Michaax). 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 f 

 bearing a long and slender spiked raceme or virgate panicle. 



3. A. gracslis, Eil. 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 

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

 ward. 



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



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



ma ny : ftoicercd spiked panicle from 6' to 18' in length. 



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

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

 the lateral rather shorter. Virginia and southward. 



5. A. pui'pui'tiscesis, Poir. Leaves glabrous, less rigid ; lower palea 

 rough or minutely serrulate-hispid on the keel and the 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, Steud.) Massachusetts to 

 Michigan, Illinois, and southward ; common. 



** *-! Culms brandling below (1 - 1 J high), the branches naked above and racemosely 

 or paniculately several- (4 -12-) flowered. 



6. A. Olig;illtlia, Michx. Spikelets large, very short-pedicelled ; glumes 

 equalling the flower, 8" -10" long, the lower 3 -5-nerved and 2-clei't at the tip, 

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



