PANicE.ii;. 79 



the upj)er glume and palea, not adherent, obcom pressed ; un- 

 furrowed; embryo hirge. 



A. Spikelets not sunken in excavations of the rachis. Some 



or all of the flowers perfect (a) 



a. Spikelets not subtended by 1 to many bristles or spines, (b) 

 b. Empty glume 1 ; spikelets acuminate, 2-ranked. . 21 



b. Empty glumes 2; perfect flower 1 (c) 



c. First empty glume with a swollen ring at the 



base, floral glume mncronate or short-awned. . 25 

 C. First empty glume without a swollen ring at 



the base (d) 



d. Spikelets usually plano-convex and obtuse, 

 sessile or nearly so, in 1 to several 1 -sided 



racemes or spikes 22 



d. Spikelets in panicles (e) 



e. All spikelets fertile 23 



e. Spikelets on the terminal panicle sterile, 



the fertile ones subterranean 24 



c. Empty glumes 2, with 1 staminate and 1 perfect 



flower, or 3 with 1 perfect flower (m) 



m. First and secpnd glumes without a callus and 



awnless 26 



m. Eachilla with membranous appendages or 



pits 27 



m. Spikelets without callus, first and second 



glumes awned 28 



m. Spikelets with a callus, the 3 empty glumes 



awned 29 



a. Spikelets single or in twos or threes, subtended by 



1 to many bristles or spines (n) 



n. Spikelets articulating above the persistent bristles. . 30 

 n. Spikelets articulating below the bristles or adnate 



spines (o) 



o. The involucre of spines more or less consolidated. 31 

 o. The involucre of few to many bristles 32 



