Erect perennial herb with a woody base and growing to about 2 m tall. Sap watery. Leaves pinnately lobed, waxy blue. Flowers large, showy, to 15 cm wide, white, fragrant. Petals 6, crinkled and crepe-like. Sepals 3 each with pointed beak towards tip, soon shed. Stamens numerous in a golden central cluster; summer. Carpel coarsely bristly.

S California, N Baja California

Although sometimes difficult to establish this species may then become difficult to remove. Grows naturally in dry areas, canyons and coastal scrub.

R. trichocalyx Eastw. Hairy Tree Poppy, differs in having rough flower buds and sepals without beaks. Hybrids between this and the described species may be encountered. [R. coulteri var. trichocalyx (Eastw.) Jeps.]

Source: Spencer, R. (1997). Papaveraceae. In: Spencer, R.. Horticultural Flora of South-eastern Australia. Volume 2. Flowering plants. Dicotyledons. Part 1. The identification of garden and cultivated plants. University of New South Wales Press.