Buckeye Trees (Aesculus sp.) are members of the same plant family (the soapberry family, Sapindaceae) as Maple trees. Like Maples, Buckeye trees are noted for their beauty. Buckeye trees can also be called "horse chestnuts"; however, they are not closely related to true chestnuts, which belong to the same plant family as oak trees.
The California Buckeye (Aesculus californica) is the only buckeye species native to California, and it is native only within California's borders. The Calscape map of its native range shows that it is native to all parts of Yolo County. Many California Buckeye trees are planted along Highway 113 between Woodland and Davis. Two California Buckeye trees were planted in John Ferns Park in 1979 when the nature area there was first installed, and one of the two is still alive to this day.
California Buckeye trees can grow as much as 40 feet tall and wide; however, depending on their environmental conditions, they quite often stay under 15 feet tall and wide. They are usually multi-trunked and at least as wide as they are tall. In spring, they cover themselves in large flower clusters that can stop traffic. The flowers are usually white, but some cultivars are available that have pink flowers. California Buckeye nectar is toxic to non-native European honeybees but poses no danger to native bee species and is an important food source for many butterflies. By July, most California Buckeyes begin going deciduous as an adaptation to survive summer drought. Their leaves turn brown early in summer but usually remain on the tree for several more months to help protect the bark from sunburn. When the leaves do drop, they reveal more of the trees' eye-catching pale gray bark and twisting branches. The trees remain leafless through fall and winter until the following spring.
California Buckeye trees prefer full sun to partial shade and average to poorly drained soil. In the Woodland area, they do not not need to be watered once established, but they can retain their leaves a bit longer with a small amount of irrigation.
Buckeye trees bear their flowers in spike-shaped clusters. The flowers near the base of the cluster are "perfect flowers," having both male and female parts. All the flowers higher up on the spike are always male flowers. Thus, all buckeye trees are androgynous but also partly male. They are ranked 7 out of 10 on the Ogren Plant Allergy Scale, indicating that it tends to cause fairly severe hay fever.