Hillside burrgrass

Robust, scrambling perennial to 1.5 m high, forming clumps or straggling over vegetation.

Leaves with sheath compressed, glabrous to pilose, smooth to slightly rough; ligule ciliate; blade flat or somewhat folded, 3–19 mm wide, scabrous, glabrous to pubescent.

Panicle spike-like, 8–24 cm long, rachis slightly flexuous; burrs 5–11 mm long, dark purplish black to pallid. Spikelets glabrous, usually 1( but up to 3) per involucre, shorter than the inner spines, 3.8–7 mm long. Lower glume 1.2–3.5 mm long, 0–3-nerved, obtuse; upper 2.4–5 mm long, 3–5-nerved, acute. Lower lemma sterile or male, 3.5–6.5 mm long, 5–7-nerved, minutely scabrous; palea slightly shorter. Upper lemma bisexual, 3.8–6 mm long, 3-nerved, minutely scabrous.