Plants perennial; loosely cespitose or the culms solitary; rhizomes elongate, 1–3 mm thick. Culms (40)60–90 cm tall. Sheathsscabrous to scabridulous; ligules 1.5–4(6) mm long, rounded to truncate; blades 20–40 cm long, (3)5–15 mm wide, flat, rather stiffly erect, narrowing to the base, glabrous, often glacuous, veins widely spaced, abaxial surface with evident cross-venation; flag leaf blades 3.5–10 cm long. Panicles 8–13 cm long, (1)2–6 cm wide, diffuse, with slender, often drooping braches and 3+ spikelets per branch. Spikelets 4.5–6 mm long. tawny or green to olive-green, sometimes infused with purple; rachilla internodes 0.2–0.5 mm long, glabrous. Glumes subequal, equaling or slightly exceeded by the tops of the bisexual florets; lower glume 4.5–5 mm long, 0.76–1 mm wide; upper glume 3.5–5.2 mm long, 1–1.8 mm wide. Lowest 2 florets staminate; lemmas usually mostly glabrous on the body, sometimes with scattered hairs, margins usually pilose, tops scabridulous, rounded, and shallowly bilobed, unawned or awned, awns to 1 mm long; first lemma 4–5 mm long, 0.75–1 mm wide, narrowly elliptic, length more than 5 times the width; bisexual floret 3.5–4.5 mm long, lemma marginspilose, particularly distally; anthers 2–3.5 mm long. 2n = 42.
Anthoxanthum occidentale grows in moist to fairly dry forested areas from Klickitat County, Washington, south to the coastal mountains of San Luis Obispo County, California. Its long flag leaves and more elongate spikelet parts make it easier to distinguish from A. hirtum than the key suggests.