Trans. Amer. Philos. Soc., n. s. 7: 355. 1840.
Perennials, to 200 cm (rhizomatous, roots fibrous). Leaves: green, blades broadly ovate to lanceolate (rarely lobed), herbaceous, bases attenuate to cuneate or broadly rounded, ultimate margins entire or serrate, apices acute, faces sparsely to densely hairy (mostly adaxially), rarely glabrous; basal petiolate, 12–30 × 3–9 cm; cauline petiolate or sessile, 5–25 × 2–10 cm. Heads in ± corymbiform arrays. Phyllaries to 3 cm (margins mostly ciliate, hairy, especially abaxially). Receptacles ovoid to columnar; paleae (proximally light-brown, distally green, becoming maroon with age) 5–7 mm, apices acute to acuminate, abaxial tips densely hairy. Ray-florets 0. Discs 17–45 × 12–20 mm. Disc-florets 200–500+; corollas yellowish green proximally, blackish maroon distally, 4–6 mm; style-branches ca. 1.2 mm, apices acute to rounded. Cypselae 3.5–5 mm; pappi coroniform, to 1.2 mm. 2n = 36.
Phenology: Flowering summer–fall.
Habitat: Open meadows, streamsides, seeps
Elevation: 1000–2800 m
Calif., Idaho, Mont., Nev., Oreg., Utah, Wash., Wyo.
Rudbeckia occidentalis is sometimes grown as an ornamental.