Native Plants: Buckeye is nonconformist plant

One of the numerous reasons to select California native plants for home landscapes is that many show different characteristics in different seasons, providing year-round interest.

California buckeye certainly fits that description. One of our showiest flowering shrub/tree species, the plant is also known for its rounded appearance, ghostly trunks and stems, curious seed capsules and large chestnut-looking seeds.

Along with native maples and box elder, California buckeye (Aesculus californica) is a member of the soapberry family. Five species in the genus Aesculus are native to North America, but our buckeye species is endemic to California, meaning it is only found in California. The plant is widely distributed — found in foothill woodlands and valleys of the Coast Range, Sierra Nevada and Tehachapi Mountains. California buckeye grows in streamside areas or on dry, hot slopes below 5,000 feet. Locally, it occurs on brushy slopes and along many of our creeks and rivers, especially in the foothills.

California buckeye is an erect or multi-stemmed shrub or small tree. Mature plants range from 12 to 30 feet tall with trunks that are 4 to 6 inches in diameter. The trunks are typically short and have numerous ascending branches. Most specimens have an overall rounded and broad shape and can be more than 15 feet wide.

California buckeye is typically summer deciduous, meaning it drops its leaves during the hot season rather than waiting until winter. The leaves are in hand-like bunches, called palmately compound, and start off a bright apple-green color when young, turning darker green as the season progresses.

At the ends of the many branches and leaf bunches are large 4- to 12-inch-long bottlebrush flower clusters. Each cluster is made of many white to pinkish petals with long spidery-looking anthers. The flowers slowly transform into large, dangling, pear-shaped seed capsules (fruits), which persist after the leaves have fallen, leaving the appearance of a decorated, but otherwise naked tree. These fruits ripen in late fall and open to reveal glossy 1- to 3-inch chestnut-brown seeds that give reason for the common names of buckeye and horse chestnut.

The plant has been the bane of beekeepers over the years, as the pollen and nectar are poisonous to European honeybees. Many buckeye plants are removed from the vicinity of apiary yards as a result.

One of nature's big teases, in my opinion, is the large seed, which otherwise looks like a great meal but is inedible. In fact, the entire plant is toxic to humans, most wildlife and livestock. Many of our native insects however, including scores of native bees, are attracted to the flowers, and the dense branch structure provides cover for many wildlife species.

California buckeye is fairly fast growing and does well in local landscapes in settings from full sun to partial or even full shade. It serves as a great specimen plant and may be complemented with various smaller shrubs, vines and grasses. The year-round activity is probably its strongest attribute. In the north state, the plant will start to burst very early, typically February. Buckeye plants have leaves long before many other species. Next are the flowers, which persist into early summer, followed by development of the seeds. The leaves wither and turn brownish-yellow, leaving the large, conspicuous seed capsules for all to see until fall. Once the seeds drop, we are left with dense and complex ghostly gray branches to admire until winter, when the cycle starts all over again.
