Subshrubs or shrubs, large, glaucous, from creeping rhizomes; sap clear. Stems herbaceous above base, branching, leafy, sparsely pilose or glabrate. Leaves alternate, petiolate; blade gray-green, 1-2× pinnately deeply lobed; primary lobes 3-5, lanceolate or ovate. Inflorescences terminal, 1-flowered; bracts present. Flowers: sepals 3, distinct; petals 6, white, obovate, crinkled; stamens many; anthers yellow; pistil 7-12-carpellate; ovary oblong to ovoid, 1-locular or incompletely to completely multilocular by placental intrusion; style absent; stigmas 7-12, flattened, coherent proximally, radiate-ascending, velvety. Fruits capsular, oblong to ovoid, bristly, dehiscing from apex. Seeds many, ovoid, 1.3-1.5 mm, aril absent. x = 19.
Both species of Romneya , closely related and sometimes merged, are cultivated widely in warm regions for their showy, white flowers, which are the largest in the family.
This project was made possible in part by the Institute of Museum and Library Services [MG-70-19-0057-19].