Ceanothus divergens  Ceanothus divergens, commonly known as Calistoga ceanothus, is an evergreen shrub in the family Rhamnaceae, an endemic of California. This plant has a growth habit described as ascending to erect and may attain height. The plant's preferred habitat is on shrub-covered, rocky, volcanic slopes. The hermaphrodite blue or purple flowers bloom in April and May. The sub-globose fruits are five to six millimeters in diameter. Occurrence is primarily in the Northern California Coast Ranges, such as near Calistoga, at altitudes of less than 500 meters.