Panicum prostratum, Lamk.
The plant is a slender annual and it consists of several branches, prostrate and creeping, with adventitious roots at the nodes below, branching or ascending above, all green or sometimes purple above and green below, 4 to 18 inches long.
The leaf-sheath is striate, 1 to 2 inches long, glabrous or very sparsely hairy, purplish above and green below or all green, keeled, margins ciliate on one side only throughout its length. The ligule is a fringe of white hairs. The nodes are glabrous or pubescent.
The leaf-blade is short or long, varying from 1/2 to 2-1/2 inches in length and 3/16 to 5/16 inch in breadth, convolute when young, lanceolate to broadly ovate-lanceolate, acute or acuminate, upper surface glabrous, and the lower glabrous or with a few scattered tubercle-based hairs; margins are very minutely serrate; base is cordate, amplexicaul with a few long slender hairs (sometimes tubercle-based), just close to the white patch on both sides on the margin of the blade about the ligule. The midrib is distinct.
The inflorescence consists of five to fifteen or twenty spikes spreading in all directions, distant or crowded; peduncle varies from 1 to 4 inches. Spikes are 1/2 to 1-3/8 inches, sessile or shortly stalked; the rachis of the spike is slender, trigonous and scaberulous.
Fig. 92.—Panicum prostratum.
A. Front and back view of spike; B. front and back view of a spikelet; 1, 2, 3 and 4, the first, second, third and the fourth glume, respectively; 3a and 4a. the palea of the third and the fourth glumes; 5. anthers, ovary and lodicules.
The spikelets are crowded all on one side, 2- to 3-seriate, ellipsoidal, 1/20 to 1/16 inch long, glabrous or pubescent, pale green or purple on one side, in pairs on pedicels, one with a slightly longer pedicel than the other; fine long hairs, varying in number from one to eight and longer than the spikelets, are found on the pedicels at their tips in some plants and not in others.