Description

Key Characters:

Growth Form: Sprawling perennials.

Stems: Culms up to 6 m long, becoming decumbent and rooting at lower nodes, branching from lower and middle nodes, internodes glabrous, hollow, thick–walled, nodes prominent, retrorsely papillose–hirsute.

Roots:

Leaves: Leaves simple. Alternate. Blades flat, up to 25 cm long, up to 15 mm wide. Surfaces usually glabrous or with a few hairs near base, midrib broad and white above near base. Margins thick, purple, scabrous. Veins parallel. Sheaths longer than internodes, papillose–hirsute to subglabrous; ligule membranous, 1.5–1.8 mm long, densely white ciliate, collar finely velvety pubescent. Stipules absent.

Flowers: Flowers in inflorescences terminal on leafy branches, up to 20 cm long, consisting of several to numerous, solitary or clustered, ascending racemes 1–7 cm long, velvety pubescent at base; spikelets solitary, paired, or in small clusters along lower sides of the trigonous rachis, the rachis up to 1 mm wide, the angles scabrous, sparsely papillose; spikelets 3.2–3.4 mm long, ovate, acute, often purple, glabrous; first glume 0.8–1.2 mm long, deltate, 1–nerved, second glume and first lemma equal, about as long as the spikelet, second glume 5–7–nerved; first lemma 5–nerved, enclosing a large palea that often protrudes between first lemma and second glume, lemma of fertile floret 2.1–2.5 mm long, elliptic–ovate, striate or rugulose; palea flat. Stamens 3. Ovary superior.

Fruit: Caryopsis infrequently developed.

Ploidy: 2n = 18; 36; 52

Habitat: Naturalized and usually forming dense mats in areas of high soil moisture or nearby open water; such as along stream banks; drainage ditches; and roadsides; as well as other disturbed sites.

Elevation Range: 0–1,060 m.