Eight species of deciduous shrubs. Leaves alternate, simple, pinnately lobed, dentate, tomentose. Flowers small, numerous, usually in large, pendulous clusters (panciles), 5 petals, rounded, 20 stamens. Fruit made up of 5 indehiscent achenes, 1-2 seeded. Native to western North America to Columbia.
The Holodiscus taxonomy is confused because H. discus, H. dumosus, and H. microphyllus are taxonomically and morphologically similar. Authorities separating these 3 closely related taxa do so based on different leaf morphologies and distributions. In the Flora of North America these 3 taxa are treated as separate and distinct species. Some authorities lump either H. dumosus and H. microphyllus or H. discus and H. microphyllus, and others recognize each of the 3 as single species. (Adapted from Forest Service, Fire Effects Information System).
Holodiscus: from the Green holo, whole; discus, disc, refers to the unlobed disc lining the hypanthium (cup around the ovary).