HITCHCOCK AND CHASE — GRASSES OF THE WEST INDIES. 279 



Spikelets awnless. 



Plants robust, 1.25 to 2 meters tall ; spathes aggregated in 

 a corymbose, usually dense inflorescence. 



19. A. bicornis. 

 Plants slender, usually less than 1 meter tall ; spathes not 

 aggregated. 

 Sessile spikelets about 3 mm. long ; blades usually not 

 over 2 mm. wide, the apex acuminate. 



20. A. leucostachyus. 

 Sessile spikelets about 4 mm. long ; blades 3 to 5 mm. 



wide, the apex boat-shaped 21. A. selloanus. 



Spikelets awned. 



Pairs of racemes few, terminal on the culms or the few 

 simple branches, the common peduncle long-exserted. 



22. A. nashianus. 

 Pairs of racemes several to many, subtended by well-devel- 

 oped spathes. 

 Blades involute; axis of raceme slender but straight. 



23. A. urbanianus. 

 Blades flat ; axis of racemes delicate and flexuous. 

 Racemes aggregated in a dense club-shaped or 

 corymbose inflorescence, the ultimate 

 spathes not over 2 mm. wide, rarely equal- 

 ing their racemes 25. A. glomeratus. 



Racemes not aggregated, the ultimate spathes 3 to 



5 mm. wide, much exceeding their racemes. 



24. A. virginicus. 



1. Andropogon fastigiatus Swartz, Prodr. Veg. Ind. Occ. 26. 1788. 

 Diectomis fastigiata H. B. K. Nov. Gen. & Sp. 1 : 193. 1816. 

 Sorghum fastigiatum Kuntze, Rev. Gen. PI. 2: 791. 1891. 



A slender erect glabrous annual with flat linear blades and firm ligules up 

 to 2 cm. long ; culms freely branching above, the racemes broad, with conspicu- 

 ous sterile spikelets and geniculate awns about 4 cm. long. 



Dry open ground, southern Mexico and the West Indies to Brazil. Origin- 

 ally described from Jamaica. 



Cuba, Jamaica, Haiti, Santo Domingo, Porto Rico, and Grenada. 



2. Andropogon brevifolius Swartz, Prodr. Veg. Ind. Occ. 26. 1788. 

 Andropogon obtusifolius Poir. in Lam. Encycl. Suppl. 1: 583. 1810. 

 Pollinia brevifolia Spreng. PI. Pugill. 2: 13. 1815. 

 Schizachyrium brevifolium Nees ; Kunth, Enum. PI. 1 : 488. 1833. 

 Sorghum brevifolium Kuntze, Rev. Gen. PL 2: 791. 1891. 



A slender trailing or reclining glabrous branching annual, with flat obtuse 

 spreading blades and delicate racemes with small spikelets and awns about 8 

 mm. long. 



Moist banks, tropical regions of both hemispheres. Originally described from 

 Jamaica ; A. obtusifolius described from Porto Rico. To be found in probably 

 all of the West Indian islands from Cuba to Trinidad. Not represented in col- 

 lections from the Bermudas and the Bahamas. 



3. Andropogon malacostachyus Presl, Rel. Haenk. 1: 337. 1830. 

 Schizachyrium malacostachyum Nash, N. Amer. Fl. 17: 102. 1912. 



A slender erect glabrous branching annual up to 50 cm. high, the flat linear 

 acute blades ascending, the numerous racemes erect, more or less fascicled, the 

 geniculate awns about 12 mm. long. 



