20 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
Racemes appressed; fruit nearly as long as the 
spikelet. 
Spikelets silky-villous, pointed.........-...-.---- 194. 
Spikelets glabrous, obtuse. ...........--+-------- 192. 
First glume much shorter than the sterile lemma. 
Spikelets hispid and with two crateriform glands on 
the sterile lemma. 
Spikelets not over 2 mm. long; blades not over 
4cm, long.........-.-.-.----+-+-+-+--e e222 eee 66. 
Spikelets 3.6 mm. long; blades 4 to 10 cm. long.. 67. 
Spikelets glabrous. 
Blades lanceolate to ovate-lanceolate; glumes 
strongly carinate; spikelets 2.3 to 2.8 mm. 
long; tropical species. 
Blades not over 5 cm., usually 2 to 3 cm. long; 
second glume rather blunt and shorter than 
the sterile lemma. ...........--.---------- 64. 
Blades 5 to 11 ecm. long; second glume acute, but 
slightly shorter than the sterile lemma. .... 65. 
Blades linear, often elongated; glumes not carinate 
or but slightly so. 
Spikelets not over 1.5 mm. long. 
Spikelets pointed, not expanded at maturity 
by an enlarged sterile palea.......-.---- 58. 
Spikelets blunt, expanded at maturity by the 
enlarged sterile palea. 
Rachis bearing slender bristles (these want- 
ing in exceptional specimens); nodes 
usually villous ............----------- 59. 
Rachis without bristles; nodes glabrous. ... 60. 
Spikelets 2.5 mm. or more long. 
Axis pilose. .........-.-------------+------- 57. 
Axis not pilose. 
Fruit transversely rugose..........------- See 
Fruit not rugose..........-2-------------- 193. 
Spikelets in open or sometimes in contracted or congested 
panicles, but not in spike-like racemes. 
Basal leaves usually distinctly different from those of 
the culm, forming a winter rosette; culms at first 
simple, the spikelets of the primary panicle not per- 
fecting seed, later usually becoming much 
branched, the small secondary panicles with cleis- 
togamous, fruitful spikelets ........---- See subgenus 
Basal leaves similar to culm leaves, not forming a winter 
rosette; spikelets all fertile. 
Fruit transversely rugose.........---------------- See 
Fruit not transversely rugose (minutely papillose- 
roughened in P. millegrana). 
. ciliatissimum. 
obtusum. 
wh 
. pulchellum. 
. biglandulare. 
ae) 
P. stoloniferum. 
P. frondescens. 
P. polygonatum. 
P. pilosum. 
P. laxum. 
P. longum. 
GEMINATA, p. 30. 
P. hemitomon, 
DICHANTHE- 
LIuM, p. 142, 
Maxima, p. 78. 
