Description

The perennial herb Helianthella castanea is a rare plant endemic to California, and is only found in the San Francisco Bay Area, mostly in and around Mount Diablo State Park. Its common names include Mount Diablo helianthella, Mount Diablo sunflower, and Diablo rockrose. A member of the daisy and sunflower family, the flowers are bright yellow and daisy-like, with ridged petals. The plant grows in clumps of green foliage and sends up flowers on long stems. It can reach 1.5' tall. It does best in full sun with well draining soil.