100 NORTH AMERICAN FLORA [VorumE 17 
mmm. wide, glabrous, or sparsely ciliate at the base, rough on both surfaces; spike-like racemes 
4-8 cm. long, the internodes shorter than the sessile spikelets, ciliate on the margins with white 
spreading hairs; sessile spikelet 4-5 mm. long, the first scale with an obtuse callus nearly 1 
mm. long, 2-nerved in addition to the hispidulous keels, the center of the upper part pilose 
with long hairs, the second scale obovate-cuneate, the keel long-ciliate, the awn 3-4 times 
as long as the scale, the fourth scale about one half as long as the second, ciliolate, elliptic, 
the awn 3.5—4.5 mm. long, glabrous, the dark-brown straight or indistinctly geniculate column 
about one half as long as the yellow subula; pedicellate spikelet with the first scale herbaceous, 
curved-obovate, flat, 15-nerved or more, bearing a straight awn as long as itself, the second 
scale half as long as the first, membranous, bearing a short awn, the fourth scale long-ciliate, 
muticous. 
TYPE LOCALITY: Jamaica. 
DISTRIBUTION : Tropics. 
ILLUSTRATION : H.B.K. Nov. Gen. & Sp. pi. 64. 
2. Diectomis laxa Nees, Agrost. Bras. 340. 1829. 
Diectomis angustata J. Presi, in Presl, Rel. Haenk. 1: 333. 1830. 
Andropogon apricus Trin. Mém. Acad. St. Petersb. VI. 42: 83. 1836. 
Andropogon angustatus Steud. Syn. Gram. 370. 1854. 
Andropogon Lindenii Steud. Syn. Gram. 389. 1854. 
Sorgum laxum Kuntze, Rev. Gen. 790. 1891. 
Stems erect, up to 1 m. tall, slender, branching above; leaf-sheaths glabrous; ligules 1-2.5 
mm. long; blades 1-3 dm. long, 1-2 mm. broad; racemes in 2’s—4’s, 1.5-2.5 cm. long, the 
common peduncle usually included in the spathe, the rachis-internodes and pedicels broadly 
cuneate, ciliate; sessile spikelet 5 mm. long, oblong, the first scale linear, truncate, the margins 
broadly infolded, the narrow intercarinal space glabrous, 2—4-nerved, the silky-barbed callus 
1 mm. long, the second scale keeled, compressed, obovate-oblong, with a straight awn 2-3 
times its length arising from the entire apex, the fourth scale gibbous on the back, 3-nerved, 
ciliate, bearing below the minutely 2-toothed apex an awn 3-4 cm. long, the hispidulous column 
geniculate above the middle and shorter than the subula; pedicellate spikelet with the first 
scale oblong, long-ciliate on the keel, 7-nerved, bearing an awn twice as long as itself, the 
3econd scale 3-nerved, shortly awned or awnless. 
TYPE LOCALITY: In sunny mountainous places, Serra dos dois Irmdos, Piauhy, Brazil. 
DISTRIBUTION : Mexico to Costa Rica; also in Colombia, Venezuela, and Brazil. 
21. SCHIZACHYRIUM Nees, Agrost. Bras. 331. 1829. 
Heterochioa Desv. Opusc. 66. 1831. 
Annual or perennial grasses, tufted or from rootstocks, with flat or involute leaf-blades, 
and spike-like racemes, singly disposed, terminating the stem or its branches. Internodes of 
the articulate rachis cup-shaped or crowned at the apex with a toothed or bifid appendage, 
the callus at the base barbed. Spikelets in pairs at each node of the frequently hairy rachis, 
one sessile, the other pedicellate. Sessile spikelet dorsaily compressed, 1-flowered, the flower 
perfect; first scale infolded on the margins, 2-keeled; second scale awnless or rarely with a 
short bristle, usually 1-nerved, or sometimes nerveless, keeled; third scale with the margins 
infolded, 2-nerved or nerveless; fourth scale usually 2-cleft at the apex, often almost to the 
base, bearing a perfect usually geniculate awn, rarely awnless, the spiral column usually 
straight, the subula sometimes loosely contorted at the base; palet usually wanting. Pedicel- 
late spikelet flowerless, of 1 or 2 scales, rarely of 4 scales and bearing a staminate flower, or 
wanting. Stamens usually 3, very rarely 1 or 2. Styles distinct. Stigmas plumose, some- 
times twice as long as the styles, exserted below the middle of the spikelet. 
Type species, Andropogon brevifolius Sw. 
Annuals. 
First scale of the sessile spikelet glabrous; internodes of the rachis glabrous or merely his- 
pidulous. 
Spikelets 3.5-4 mm. long; leaf-blades short, obtuse; stems prostrate. 1. S. bvevifolium. 
Spikelets 4-5 mm. long; leaf-blades long, acute; stems erect. 2. S, Gaumeri. 
First scale of the sessile spikelet white-villous on the back; internodes 
of the rachis densely clothed with white hairs on the back and 
margins, ‘ 3. S. malacostachyum. 
