Fl. Calif. 1: 266. 1921.
Stems 1–1.5 m, grayish-hairy distally. Leaf blades elliptic, distal lanceolate, 10–35 × 7–21 cm, reduced distally, grayish-hairy, at least when young. Inflorescences paniculate, with ascending branches, 20–50 cm, grayish-hairy; bracts ovate to lanceolate, shorter than flowers. Tepals creamy white to yellow, broadly ovate, not clawed, 6–15 mm, margins strongly erose-ciliate or inner shallowly fimbriate; gland 1, basal, green, V-shaped, elliptic; ovary densely tomentose; pedicel 6–15 mm. Capsules oblong-ovoid, 2–3 cm, densely tomentose. Seeds flat, broadly winged, 10–15 mm. 2n = 32.
Phenology: Flowering summer–fall.
Habitat: Stream banks, moist meadows, mixed-evergreen forest margins
Elevation: 0–1500 m
Calif., Oreg., Wash.
The only other whitish-flowered species in North America, Veratrum californicum, which might be confused with V. insolitum, has entire, unfringed tepals, and only slightly hairy ovaries.