Andropogon pertusus, Willd.
This grass is perennial. Stems are tufted, very slender, widely creeping on all sides, purplish, but the flowering branches are erect or ascending from a geniculate base, leafy at base, the nodes of the creeping branches rooting and bearing tufts of branches which finally become independent plants at each node, the creeping branches vary in length from 1 to 3 feet and the erect ones from 10 to 18 inches or more.
The leaf-sheaths are terete or somewhat compressed, glabrous, sometimes ciliated near the node and shorter than the internode. The ligule is a truncate membrane, slightly ciliate or not. Nodes are bearded.
The leaf-blades in the prostrate branches are crowded, short linear-lanceolate, finely acuminate, soft, shortly hairy along the nerves, sparsely ciliate near the rounded base, varying in length from 1 to 2 inches and in breadth 1/8 to 1/4 inch; but on the flowering branches the leaves are longer, sometimes as long as twelve inches with bigger sheaths.
Fig. 153.—Andropogon pertusus.
1. A portion of a spike; 2. a pair of spikelets; a. sessile and b. pedicelled; a-1. first glume; a-2. second glume; a-3. third glume; a-4. fourth glume and awn; a-5. ovary and stamens; a-6. grain; b-1. first glume of pedicelled spikelet front and back; b-2. second glume front and back; b-3. third glume.
The inflorescence consists of three to nine, slender, flexuous, erect, purplish spikes, 1 to 2 inches long, alternately arranged on a thin, long, slender, smooth peduncle of about six inches; rachis is slender and the joints and pedicels are densely silky with long hairs.
The spikelets are in pairs, one sessile and one-pedicelled, both are equal, purplish or pale. The sessile spikelet consists of four glumes and contains a complete flower and the callus is short and bearded with long hairs. The first glume is coriaceous, oblong-lanceolate, acute, truncate or emarginate, slightly hairy, or glabrous with a deep pit above the middle (sometimes with two or three pits also) 7- to 9-nerved with a few long hairs below the middle and with margins infolded and shortly ciliate. The second glume is lanceolate-acuminate and finely pointed at the tip and the point projecting slightly beyond the first glume, 3-nerved or 3- to 5-nerved, membranous, slightly hairy or glabrous, obscurely keeled. The third glume is thin, membranous, shorter than the second glume, linear-oblong, subobtuse or acute at the tip and nerveless. The fourth glume is the base of the awn and the awn is not twisted, bent at about the middle, 1/2 to 2/3 inch long; there is no palea. Anthers are three and yellow; stigmas purple. The grain is oblong-obovate, slightly transparent.
The pedicelled spikelets are slightly narrower than the sessile, generally not pitted (though pitted in some plants), and not awned, and each one consists of three glumes only; the pedicel is more than half as long as the sessile spikelets. The first glume is slightly hairy, oblong-lanceolate, acute or obtuse, ciliate at the margins, 7- to 9-, or 13-nerved, generally without pits, but occasionally with one, two or three pits; the keels are ciliolate throughout the length. The second glume is membranous, ovate-lanceolate, acute, with incurved margins, 5-nerved. The third glume is hyaline, linear-oblong, glabrous and thinly ciliate at the tip or not with or without stamens.