Description: This native grass is a summer annual about 1½–3½' tall. An individual plant often branches at the base, sending up multiple culms that can sprawl or stand erect; each of these culms is unbranched. The culms are light green, terete, and glabrous. The blades of the alternate leaves are up to 16" long and ¾" across; they are green or blue-green, linear in shape, rather floppy, and usually hairless. Sometimes a leaf blade may have a few long hairs near its base. The leaf sheaths are the same color as the blades and usually hairless; however, some sheaths have short fine hairs.
Each culm terminates in a panicle of spikelets up to 10" long. The branches of this panicle are up to 2½" long; they spread outward as the panicle matures. The spikelets are arranged on one-side of each branch; they are densely distributed along its length. The spikelets are light green to dark green and more or less covered with fine hairs; sometimes they become purple or dark red in bright sunlight. Each spikelet consists of 2 glumes, 2 lemmas, and a floret; it is ovoid in shape and about 3-4 mm. long (excluding any awn). The first glume is about 1/3 the length of the spikelet, while the second glume and infertile lemma form the exterior of the spikelet. In this variety of Barnyard Grass, the infertile lemmas usually have awns about 3-10 mm. long; less often, they have awns up to 25 mm. (1") long. The fertile lemma is hidden from view behind the awnless second glume; it encloses the floret on one side, which has 2 feathery stigmas, 3 stamens, and an ovary. The blooming period can occur from mid-summer to early fall. The florets are wind-pollinated. Each spikelet produces a single grain that is about 3 mm. long, ovoid, and somewhat flattened. The root system is shallow and fibrous. This grass spreads by reseeding itself, and it often forms colonies at favorable sites.