It is a tufted annual with numerous radiating branches, growing on all directions, bent below and erect above; they vary in length from 6 inches to 18 inches, but sometimes when growing under favourable conditions attain the length of 2-1/2 feet. The stem is slender, green, or pale reddish in the exposed portions and pale in parts covered by sheaths slightly flattened, smooth. The _leaf-sheaths_ are smooth, compressed, distinctly keeled. The _ligule_ is a short, truncate, white, glabrous membrane. The _nodes_ are glabrous. The _leaf-blade_ is linear, finely acuminate, glabrous, but sometimes somewhat scabrid along the nerves and with scattered long delicate hairs above especially when young, varying in length from 1 to 7 inches and 1/10 to 1/8 inch in breadth. The _inflorescence_ consists of paired spikes with very slender peduncles arising from flattened, glabrous, acuminate spathes, varying in length from 1/2 to 1-1/4 inches. The _spikes_ are spreading and one of them always slightly longer than the other, reddish or pale green, 1/2 to 1 inch long; the _rachis_ consists of five to eight flat joints broadened at the top and ending in a cup, densely ciliate on both the margins, but hairs on one margin are shorter than those on the other. Each joint bears a sessile and a pedicelled spikelet. [Illustration: Fig. 151.--Andropogon pumilus. 1. A portion of the spike to show the arrangement of the spikelets; 1. the first glume of the sessile spikelet; 2. second glume of the sessile spikelet; 3 and 4. third and fourth glumes of the sessile spikelet; 5. anthers, lodicules and the ovary; A, B and C. the three glumes of the pedicelled spikelets.] The _sessile spikelet_ is about 3/16 inch with an awn 7/16 inch long. There are four _glumes_ in the spikelet. The _first glume_ is narrow, linear, membranous, grooved, finely bicuspidate at the apex, with incurved margins and two nerves ending in tubercles below. The _second glume_ is a little longer than the first, narrow, lanceolate, boat-shaped, thinly coriaceous with membranous margins, 1-nerved and shortly awned. The _third glume_ is about 2/3 of the second glume in length, and shorter than the first glume, linear-lanceolate, hyaline, nerveless or sometimes very obscurely 2-nerved. The _fourth glume_ is narrow linear, hyaline with two very fine lobes at the apex with an awn between, 7/16 inch long. _Palea_ is hyaline and very small. _Stamens_ are three, _ovary_ with two long reddish feathery _stigmas_. _Lodicules_ small and cuneate. Grain is long and narrow. The _pedicelled spikelets_ have only three glumes, and are slightly shorter than the sessile ones, pedicel is similar to the joint. The _first glume_ is ovate-lanceolate, thinly coriaceous, distinctly many-nerved, acuminate, margins infolded and membranous. The _second glume_ is ovate-lanceolate, membranous, glabrous and 3-nerved. The _third glume_ is short, oblong-lanceolate, nerveless or faintly 2-nerved. There are three stamens.