356 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
5. Cenchrus gracillimus Nash, Bull. Torrey Club 22: 299. 1895. 
Differs from C. carolinianus in the erect more slender culms, longer narrow 
blades, and smaller glabrous, less crowded burs. 
Sandy soil, Florida and Jamaica (southern Manchester). Originally de- 
scribed from central Florida. 
6. Cenchrus microcephalus Nash, sp. nov. 
Culms compressed, slender, 3 to 7 cm. long, ascending from a decumbent 
base; blades commonly 12 to 15 cm. long, about 2 mm, wide, sparsely pilose on 
the upper surface; burs about 10, scarcely 5 mm. long, erect, smaller than those 
of any other species of the West Indies, the flattened spines ciliate; spikelets 
usually 2 in each bur, 4 mm. long. 
Type specimen in the herbarium of the New York Botanical Garden, collected 
in saline meadows, Berry Island, Bahamas, by Britton & Millspaugh (no. 2249). 
Kknown only from the Berry Islands, a second specimen collected on Frozen Cay 
(Britton & Millspaugh 2211). 
7. Cenchrus echinatus L. Sp. Pl. 1050, 1753. 
Cenchrus brevisetus Fourn, Mex. Pl. 2: 50. 1886. 
Culms usually about 50 cm, long, ascending from a decumbent base, branch- 
ing below; blades flat, thin, usually elongate, 5 to 10 mm. wide; spike commonly 
5 to 7 cm. long. This species is extremely variable in the size of the burs and 
length of bristles. Small-burred specimens may be distinguished from C. 
viridis by the fewer, less-crowded burs and stiffer bristles. 
Open ground and waste places. A common weed throughout the warmer 
parts of America. Originally described from Jamaica and Curacao. Cenchrus 
brevisetus was described from Mexico. 
To be found on probably all of the West Indian islands. 
CENCHEUS INSULARIS Scribn. in Millsp. Field Mus. Bot, 2: 26. 1900. From 
Mexico to northern South America. Originally described from Alacréin Shoals 
off the coast of Yucatan. A single immature specimen that may belong to this 
species comes from Chacachacare Island, Trinidad (Hitchcock 10056). This 
species differs from C. echinatus in having larger burs with a densely villous 
base. 
8. Cenchrus viridis Spreng. Syst. Veg. 1: 301. 1825. 
Cenchrus echinatus var. viridis Spreng.; Griseb. Fl. Brit. W. Ind. 556. 1864. 
Taller than C. echinatus, more upright, the spikes commonly 10 em. long. 
Open ground and waste places, Florida to Central America and the West 
Indies. Originally described from Guadeloupe. To be found on probably all 
of the West Indian islands. 
51. STENOTAPHRUM Trin. 
Spikelets 2 or 3 together in reduced racemes, these embedded in cavities along 
one side of a broad flat thickened corky articulate axis, the spikelets falling 
attached to the joints; spikelets strongly convex on the inner side; first glume 
minute. 
1. Stenotaphrum secundatum (Walt.) Kuntze, Rev. Gen. Pl. 2: 794. 1891. 
St. AUGUSTINE GRASS. 
Ischaemum secundatum Walt. Fl. Carol. 249. 1788. 
Rottboellia stolonifera Poir. in Lam. Encycl. 6: 310. 1804, 
Stenotaphrum americanum Schrank, Hort. Monac. pl. 98. 1811-1818. 
Stenotaphrum sarmeéntosum Nees, Agrost. Bras. 93. 1829. 
