[Wikipedia] Rarity, Habitat, Conservation: Ceanothus roderickii is a rare species of shrub in the family Rhamnaceae known by the common name Pine Hill ceanothus. It is endemic to western El Dorado County, California, where it grows in the chaparral and woodlands of the Sierra Nevada foothills, such as the Pine Hill Ecological Reserve. It is named after 20th century California flora explorer, botanist, and arboretum director Wayne Roderick. Habitat Ceanothus roderickii is found almost exclusively on soils of gabbro origin in the Pine Hill Geological Formation.[1] It is a federally listed endangered species. Conservation This endangered plant was first collected in 1956 near Shingle Springs.[1] It is threatened by several factors, including suppression of the wildfire it requires for reproduction, off-road vehicles, road maintenance and construction, and development.[2] There are ten[1] to twenty[3] remaining occurrences. (link added by Mary Ann Machi)