Summer holly (Comarostaphylis diversifolia) is found in coastal chaparral from Santa Barbara County southerly into Baja California. There may be populations on the Channel Islands as well. Some sources cite that the geography makes for two subspecies: Comarostaphylis diversifolia ssp. diversifolia in coastal Southern California and Baja; and Comarostaphylis diversifolia ssp. planifolia on the Channel Islands and the Transverse Ranges north of Los Angeles. It is not very common, but not yet listed as rare.
A slow‐growing, evergreen shrub or tree to 20 ft. tall. Attractive features include shiny leaves, white flowers, red berries and shredded bark. While the flowers are urn-shaped similar to the more familiar manzanita, the red berries are warty or wrinkly rather than smooth. That feature also distinguishes it from toyon. Summer holly is a member of Ericaceae, commonly known as the heath or heather family, a family of flowering plants found most commonly in acid and infertile growing conditions.