Bill Grave's Jasper Ridge Page: Dirca expert, Bill Grave's webpage at Jasper Ridge (contributed by Roy West)

[Wikipedia] Description, Habitat, Rarity: Dirca occidentalis, the western leatherwood, is a deciduous shrub with leaves three to seven centimeters in length. Yellow flowers emerge prior to leafing. It grows on moist and shaded slopes. It is rare[2] and endemic to the San Francisco Bay area of California. Its closest relative, Dirca palustris, lives in the eastern half of North America. (contributed by Mary Ann Machi)

Dirca occidentalis: Dirca occidentalis (western leatherwood) is a rare shrub that is native to California and endemic (limited) to California in the San Francisco Bay area. Its low growth, dispersal, and germination rates limit how quickly populations can recover from loss. Its very low seed dispersal rate may suggest that its natural disperser disappeared from the region. (contributed by Cynthia Powell)