550 geaminejE. (gkass familt.) 



15. ARISTIDA, L. Triple-awned Gkass. 



Glames unequal, often biistle-pointed. Lower palea tipped with three awns ; 

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

 ing : leaves narrow, often involute. Spikelets 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 the 

 end of summer. 



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

 1- Awns very unequal ; the 2 lateral merely short erect bristles, scarcely I or I 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. dicIl6tOina, Michx. (Povekty Grass.) Culms erect or ascend- 

 ing; spikelets small, mostly crowded and panicled; glumes \-nerved, k'-\ 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, S-f>-nervcd, about 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- 

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

 the palea only 1 J" - 2" long. Ligule truncate, bearded. 



-1- H- Awns unequal but similar ; the 2 lateral about half the length of the horixontally 

 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. g^r&cilis, EU. Culms slender, erect (6'- 18' high); flower as long 

 ' as the glumes (2j"-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. 



^- -1- ^- Awns nearly equal, divergently spreading : root perennial. 

 ** Culms simple or nearly so {1° -2° high), terminated by a long and strict virgate 

 many flowered spiked panicle from 6' to 18' in length, 

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

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

 the lateral rather shorter. — Virginia and southward. 



5. A. purpur&sceiis, 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, MuJil. A. Geyeriana, Steud.) — Massachusetts to 

 Michigan, Illinois, and southward ; common. 



++ -<-<• Culms branching below (1° -l^° high), the branches naked above and racemosdy 

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



6, A. olig'^nttia, Michx. Spikelets large, very short-pediccllcd ; glumes 

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

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



