PANK'E.E. 79 



the upper gliiiue tiiul ptilea, not adliereut, obconi pressed ; un- 

 t'lUTowed; embryo large. 



A. Spikelets not sunken in excavations of tlie racliis. Some 



or all of the flowers })erfect (a) 



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

 b. Empty glume 1 ; spikelets acuminate, 3-ranked. . 21 



b. Empty glumes '^; i)erfect flower 1 (c) 



c. First empty glume with a swollen ring at the 



base, floral glume mucromito 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 23 



d. Spikelets in panicles (c) 



e. All spikelets fertile 2:5 



e. Spikelets on the termimd panicle sterile, 



the I'cn'tile ones sul)terranean 24 



C. Empty glumes 2. with 1 staminate and 1 perfect 



flower, or 3 with 1 perfect flower (m) 



m. First and second glumes without a callus and 



aunless 20 



m. KiK'hilla with membranous ajipendages or 



pits 2: 



m. Spikelets without callus, lirst and second 



glunu's awned 28 



m. Si)ikelets with a callus, the 3 empty glumes 



awned 29 



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



1 to many bristles oi- spines (u) 



n. Spike'ets articulating above \\\v persistent bristles. . 30 

 n. S})ikelets articulating l)eIo\v the bristles or admite 



spines (o) 



o. 'i'he involucre of spines more or less consolidated. 31 

 o. The iuvohu'iv of few to many bristles 32 



