Contr. Dudley Herb. 1: 225, plate 20. 1936.
Stems 1–2 m; herbage harshly and moderately stellate-hairy. Leaf blades deeply (3-), 5-, or 7-lobed, 8–20 cm wide, lobes broadest at middle, base truncate to cordate, margins serrate or irregularly dentate. Inflorescences cymes, forming interrupted spikes or racemes; involucellar bractlets broadly elliptic-lanceolate to ovate, 10–14 × 4–6 mm, equaling or exceeding calyx. Flowers: calyx 8–10 mm, lobes triangular-ovate, 5–8 × 4–5 mm, slightly longer than broad, slightly longer than tube; petals rose-purple, 2–3 cm. Schizocarps 10–15 mm diam.; mericarps 10–14, 6–8 mm. Seeds 2 or 3, dark brown, 2 mm, puberulent.
Phenology: Flowering Jun–Aug.
Habitat: Conifer forests, streamsides, sometimes shaded
Elevation: 500–2000 m
Iliamna latibracteata is distinctive in having large involucral bracts, which more or less envelop the calyx and equal or surpass it in length. It occurs in the Klamath and Siskiyou mountains of Del Norte and Humboldt counties in California, north to Coos, Curry, Douglas, Jackson, and Josephine counties in Oregon, with an eastern outlying station reported from Mount Shasta, California.