These are perennial or annual grasses with varied habit. Inflorescence is an open or contracted or spiciform panicle. Spikelets are small consisting of three membranous glumes, 1-nerved or nerveless. The first and the second glumes are unequal, persistent or separately caducous. The third glume is ovate or oblong, acute or obtuse, longer or shorter than the second, 1-nerved, paleate; palea is as long as the glume and of the same texture of the glume dorsally narrowly inflexed along the middle line and splitting into two halves. Lodicules are very minute or absent. Stamens one to three. Styles are with short stigmas. Grain oblong, obovoid or round.
KEY TO THE SPECIES.
- Glumes I and II both shorter than III.
- Panicle rather narrow with short capillary branches; glumes I and II nerveless. 1. S. diander.
- Glume I shorter than II and III and II nearly or quite as long as III.
- Panicle contracted, narrow and spiciform; glume I 1-nerved. 2. S. tremulus.
- Panicle open and effuse.
- Branches with spikelets and pedicels appressed. 3. S. coromandelianus.
- Panicle short; leaves glabrous.
Branches with pedicel and spikelets drooping and not appressed. 4. S. commutatus. - Panicle large; leaves with long hairs. 5. S. scabrifolius.
Sporobolus diander, Beauv.
This is a tufted annual or perennial grass. Stems are slender with leaves tufted at the base, 1 to 3 feet high.
The leaf-sheath is glabrous and smooth, ribbed, the lower short and the upper very long. Nodes are glabrous. The ligule consists of a fringe of minute hairs.
The leaf-blades are usually flat, glabrous, strongly nerved, with filiform tips, 3 to 10 inches by 1/25 to 1/16 inch.
The inflorescence is an erect narrow pyramidal panicle, varying in length from 4 to 10 inches and about 2 inches in breadth. The branches are very fine, spreading and in scattered fascicles, 1/2 to 2 inches long, with many very small spikelets arranged racemosely along the axis. Spikelets are small 1/18 to 1/20 inch long, with very short pedicels. The first glume is very short less than 1/5 inch, broadly oblong, nerveless, hyaline, broadly truncate and erose at the apex. The second glume is a little longer than the first, but shorter than the third, hyaline, broadly elliptic-oblong, nerveless or obscurely 1-nerved. The third glume is broadly ovate-oblong, subacute, 1-nerved, paleate; the palea is plicate in the median line. Stamens are usually two. The grain is obovoid, truncate at the apex, and with a small white swelling in the centre at the apex, rugulose, red-brown.