California buckeye can grow to be 12-40 feet tall. It has thin grey bark that is often covered with lichens. The leaves are dark green, palmately compound with 5 to 7 leaflets. Each leaflet is 2.4-6.7 inches long, with finely-toothed margins. The flowers are sweet-scented, white to pale pink, borne on erect panicles 6-8 inches long. Most of the flowers in each cluster are male and, thus, incapable of producing seeds; only two or three at the tip are fertile and will produce the actual buckeyes, which ripen in the fall. The fruit is a fig-shaped husk 2-3 inches long, containing a large, round, orange-brown seed.
Well adapted to California's Mediterranean climate with wet winters and dry hot summers,the California buckeye has adapted by growing during the late winter & spring and entering dormancy in the summer. Shortly after it flowers, its leaves turn yellow or brown and begin to wither and fall. This continues throughout the summer. Native Americans ate the buckeye seeds, but they are poisonous in their raw state, so they ground the nuts to leach out all the saponins before cooking them.