11)0 I'OACK.K. 



(1. Klonil .uliiiiic na'.''")\v. ut^iiully with u tnirvcMl 

 sliiirp-pointod hairy callus, iinil a stout, twisted 



and iHTsistoiit awn 4(i 



d. Flonil tjhiiiu' broad, with a very stout blunt 

 callus, and a weak terminal eadueous tortuose 



iiwn 47 



d. Floral <jhnne ventrieose. with a short, stout. 

 Hat, obli(|Ue callus and a short, straight or 



curved awn 48 



c. Lodicules 'i: awns slender, sometimes minute. 

 Palea nu'mhranous, closely enclosin<j the grain. 



Spikelets small 50 



c. Floral glume broad, deeply "^-toothed and with 

 palea oidy loosely enclosing the grain. . . .51 

 b. Floral glume awnless 4!) 



p" 



b. Floral glume with a straight terminal awn. liachilla 



prolonged above the palea 51 



a. Spikelets in pairs, one containing a perfect ilower. the 

 other staminate or sterile, forming the spikclike pani- 

 cle 5;{ 



a. The spik(>lets containing perfect flowers surrounded at 

 the base by numerous sterile (and a few staminate) spike- 

 lets which are red uci'd to bristles or bracts 54 



B. Floral glume usually hyaline or membranous at maturity, not 

 so firm as tiie I'lnpty glumes; grain loosely or not at all en- 

 closed (a) 



a. Empty glumes none; s])ikelets in umbel-like clusters, 



pauictdate; stanu'us '2, plants very small 5S 



a. Empty glumes present (b) 



b. Falea ^-nerved; stamen 1; floral glume raiseil on a 



distinct naked (^allus, panicle loose 05 



b. Palea usually none, if present small ami keeled; 

 spikelets in a dense spikelike panicle or head; floral 



glume usiudly with a bent dorsal awn 57 



b. Palea usually present, 2-nerved (c) 



