Giant blazingstar Giant blazingstar

Mentzelia acuminata (Rydberg) Tidestrom

Leaf blades 39.8–154 × 8.4–40.4 mm, widest intersinus distance 4.9–24.6 mm; proximal oblanceolate to elliptic, margin lobes 18–44, 2.5–8.9 × 3.6–9.6 mm; distal with base clasping or non-clasping, margin lobes 14–42, 2.1–6.1 × 3.2–6.3 mm; adaxial surfaces with needlelike trichomes. Bracts 13–29 × 1–5 mm, margins entire or pinnate. Flowers: petals 43–70 × 8–17.3 mm; 5 outermost stamens 39–55 × 1–2(–2.5) mm. Capsules cylindric, 22–43 × 8–11.1 mm. Seed coat: papillae 4–11 per cell.

Flowering May–Oct. Dry streambed bottoms and banks, gravel bars, hillside slopes, roadsides, roadcuts, sand dunes; 0–3000 m; Ariz., Calif., Idaho, Mont., Nev., Oreg., Utah, Wash., Wyo.