Panicum porphyrrhizos Steud.

Robust annual or short-lived perennial; culms 50–200 cm. high, 2–4 mm. in diameter at the base, erect; nodes glabrous, not sharply demarcated, pale or dark, the pigment diffusing above and below the nodes.. Leaf-blades linear, 15–30 cm. long, 5–10 mm. wide, straight at the base, flat, glabrous, rarely sparsely hairy, acuminate.. Panicle ovate to oblong, (20–)30–50 cm. long, much branched and spreading, the spikelets tending towards the extremeties of the branches and appressed to them.. Spikelets ovate, 3.5(–4) mm. long, pale, often tinged with purple, acuminate to cuspidate; lower glume broadly ovate, 1/4–1/3 the length of the spikelet, membranous, 1–3-nerved, cuff-like, clasping the base of the spikelet, acute to acuminate; upper glume ovate, as long as the spikelet, membranous, 7–9-nerved, acuminate; lower lemma similar to the upper glume, sterile, its palea poorly developed; upper lemma pale and glossy.

By ditches and on moist soils.