8. Setaria, Beauv.
These are usually annuals. Inflorescence is usually a spike-like panicle. Spikelets are 1- to 2-flowered, jointed on very short pedicels which bear persistent scabrid or barbed bristles (modified branchlets). There are four glumes. The first glume is the shortest, equal to about half the length of the third, membranous, 3- to 5-nerved. The second glume is equal to or shorter than the fourth, 5- to 7-nerved. The third glume more or less exceeding and resembling the second glume, neuter, rarely paleate and male. The fourth glume is coriaceous or crustaceous, plano-convex, bisexual, 5-nerved and paleate; palea is as long as the glume. Lodicules are broadly cuneate. Stamens are three. Stigmas are laterally exserted. Grain is tightly enclosed by the hardened glume and its palea and is oblong or ellipsoid.
KEY TO THE SPECIES.
- Bristles with spreading or erect barbs.
- Inflorescence cylindric, continuous and not interrupted, with six to twelve bristles in the involucel 1. S. glauca.
- Inflorescence interrupted, with three to six bristles in the involucel 2. S. intermedia.
- Bristles with reversed barbs 3. S. verticillata.
Setaria glauca, Beauv.
This is a tufted annual grass. Stems are slender, simple or branched, erect or ascending.
The leaf-sheaths are glabrous. Nodes are glabrous and sometimes the lower are rooting. The ligule is a fringe of long hairs.
The leaf-blades are lanceolate-linear, flat, finely acuminate, with a rounded base and very finely and minutely serrate margin, glabrous on both the surfaces or occasionally sparsely hairy on the upper surface and varying in length from 4 to 12 inches or more, and in breadth from 1/4 to 1/3 inch.
The inflorescence is a cylindric, densely flowered, spike-like raceme, 1 to 4 inches long, usually yellow, rarely purplish or pale green, the bristles of involucels vary from six to twelve and are pale or reddish brown, 1/6 to 1/3 inch long with fine erect or spreading barbs.