HITCHCOCK AND CHASE—GRASSES OF THE WEST INDIES. 303 
Spikelets not lacerate-margined. 
Inflorescence a large flabellate panicle of numerous racemes, the spikelets 
solitary. 
Spikelets glabrous _.---___..-----= 51. P. fasciculatum. 
Spikelets with long silky hairs on the Inargin; racemes very slender, 
60. P. saccharoides. 
Inflorescence not flabellate, or if slightly so the spikelets in pairs. 
Racemes 2, conjugate at the summit of the culm, rarely a third below. 
Spikelets elliptic or narrowly ovate. 
Culms erect, not stoloniferous nor rhizomatous________ 20. P. neesii., 
Culms ascending or erect from creeping stolons or rhizomes. 
+ Second glume pubescent; spikelets somewhat turgid. 
7. P. distichum. 
Second glume and sterile lemma glabrous; spikelets flattened. 
Blades erect or ascending, involute-setaceous__6. P. distachyon. 
Blades spreading, tapering from base to apex, the margins in- 
volute - - 5. P. vaginatum. 
Spikelets suborbicular, broadly ovate or obovate. 
Spikelets concavo-convex, sparsely long-silky around the margin; 
plants stoloniferous__ - 50. P. conjugatum. 
Spikelets plano-convex, not silky-margined. 
Spikelets 1.5 mm. or less long, more or less pubescent. 
Plants annual; spikelets or some of them sprinkled with globular 
hairs w~a-- eee 45. P. multicaule. 
Plants perennial; spikelets minutely pubescent. 
° 47. P. clavuliferum. 
Spikelets 1.8 to 3 mm. long, glabrous. 
Spikelets golden brown, transversely marked with dark lines. 
13. P. serpentinum. 
Spikelets green, not marked. 
Sheaths pubescent; spikelets about 1.8 mm. long. 
12. P. pumilum. 
Sheaths glabrous or sparsely ciliate only, 
Spikelets less than 2.5 mm. long 11. P. minus, 
Spikelets 2.5 to 8 mm. long _-_.._---_-______ 10. P. notatum. 
Racemes 1 to many, racemose or fascicled on the axis, not conjugate, 
Second glume wanting; sterile lemma dark crimson. 
59. P. pulchellum. 
Second glume present. 
First glume present on at least one of the pair of spikelets, 
Spikelets pubescent _---------- ee 43. P. ciliiferum. 
Spikelets glabrous. 
Spikelets 1.5 mm. long_ - -41. P. decumbens, 
Spikelets 2.6 to 3 mm. long. 
Plants with hard scaly rhizomes_________ 57. P. unispicatum. 
Plants more or less stoloniferous but having no rhizomes, 
58. P. pilosum. 
First glume normally wanting (rarely present on occasional spike- 
lets). 
Fruit dark brown and polished (see also no. 52 with brown but not 
polished fruit). 
Plants annual, 
® 47877 °—_17——_4 
