Native Plant Fun Facts -- The Distinctive California Buckeye

Today’s featured native plant is Aesculus californica (California Buckeye; California Horse Chestnut). This tree / large shrub is currently in bloom in San Francisco, and its panicles (elongated groupings of flowers) have delicate white flowers with brown or reddish stems. These flowers are terrific support for hummingbirds, many types of butterflies, and native bees, but not for honeybees, which are not native to our continent (most honeybees in the U.S. are of European origin) and for whom the flowers are toxic. Pollinated flowers develop into round, leathery capsules that have large seeds (1 - 2.5” diameter) that do indeed look like deer eyes! 

An Aesculus california tree hanging over a retaining wall on Laguna Honda Boulevard (near Clarendon) in San Francisco.

Aesculus californica is summer deciduous, which means it loses its leaves in California’s summer dry season and begins getting new leaves in the winter rainy season. This may sound odd, but when you consider that this coincides with when its habitat gets rain, it makes perfect sense! While Aesculus californica can make a seasonally attractive plant with its delicate leaflets radiating from a central point and its silvery-grey bark, keep in mind that it may be devoid of leaves when many other plants in your garden are at their peak appearance. 

A young, developing Aesculus californica panicle.

Some of California’s native peoples found parts of the plant medically useful -- Costanoan and Mendocino people used the bark for toothache relief, and Costanoan and some Pomo people used the toxic seeds sprinkled in rivers to stun fish for easy capture for food. The seeds can be leached of the toxic tannins (much like acorns) and then ground, roasted, or boiled for eating. 

Developing more! The redness of the stem is beginning to appear.

If you’d like to plant a tree that’s long-lived, Aesculus californica is the one! It can live up to 300 years, so an investment in one will provide beauty and ecological support for generations to come. We hope you’re able to go out and find a tree near you so that you can see its beautiful flowers and foliage for yourself! 

Several gorgeous panicles in full glory on an Aesculus californica in Noe Valley, San Francisco.