HITCHCOCK AND CHASE—GRASSES OF THE WEST INDIES. 325 
Spikelets hispid and with 2 crateriform glands on the sterile 
lemma ~___- ~-----------+------ 39. P. pulchellum. 
Spikelets glabrous, glandless; second glume and sterile lemma 
boat-shaped. 
Blades not over 5 cm., usually 2 or 3 cm., long; second glume 
rather blunt and shorter than the sterile lemma. 
37. P. stoloniferum. 
Blades 5 to 11 cm. long; second glume acute, nearly equaling 
the sterile lemma___-___-__--_-_-_- 38. P. frondescens. 
Blades linear, often elongate; spikelets glabrous. (Laxa in part.) 
Spikelets not expanded at maturity by an enlarged sterile 
palea, pointed; nodes densely pubescent. 
30. P. polygonatum. 
Spikelets more or less expanded at maturity by the enlarged 
sterile .palea, mostly blunt. 
Blades narrowed toward the base_____-_._-__ 34. P. laxum. 
Blades cordate or truncate at the base. 
bd Spikelets 2 mm. long; panicle branches erect or nearly so. 
85. P. stevensianum. 
Spikelets not over 1.6 mm. long, usually less; panicle 
branches spreading or ascending. 
Panicles one-third to half as wide as long; spikelets not 
conspicuously secund, somewhat irregularly dis- 
posed; blades cordate-clasping__.33. P. boliviense. 
Panicles rarely one-fourth as wide as long; spikelets 
conspicuously secund and regularly disposed. 
Culms as much as 2 meters long; panicles 25 to 30 cm. 
long; Trinidad____-__________ 81. P. milleflorum. 
Culms not over 1 meter long; panicles 5 to 15 cm. long. 
32. P. pilosum. 
Spikelets in open or sometimes (AGRosTorp14, TENERA) in contracted 
or congested panicles, but not in 1-sided spikelike racemes. 
Sterile palea enlarged and indurate at maturity, expanding the 
minute spikelets; spikelets clustered along the ends of the 
branches __-36. P, exiguiflorum. 
Sterile palea if present not enlarged. 
Fruit sparsely silky-pubescent; first glume very small, not over 
one-fourth the length of the small obovate blunt glabrous 
spikelets - -- _40. P. schiffneri. 
Fruit glabrous; first glume usually more than one-third the length 
of the spikelet, if shorter the spikelets not obovate nor blunt. 
First glume short, blunt; spikelets pointed; base of culm 
usually decumbent, rooting at the nodes. (DiIcHOTOMI- 
FLORA in part.) 
Fruit not acuminate; panicles rarely over 18 cm. long. 
12. P. aquaticum. 
Fruit acuminate; panicles often 40 cm. long; culms succu- 
lent; aquatic _-18. P. elephantipes. 
First glume usually more than one-third the length of the 
spikelet. 
Plants forming conspicuous hard creeping scaly rhizomes. 
(Vigaata.) 
