June on the Watershed: California Buckeye Bursting Out

It’s a showpiece of the watershed. The deciduous California buckeye tree is in its full pink and white bloom, and the fragrant blossoms are an annual staple for others in the oak woodland community. 

The nectar draws more butterflies than any other native plant, and the pollen is feast for a diversity of bumble bees, beetles and other native insects. The Echo blue butterfly lays its eggs on the new unopened bud, which then becomes host for the larvae that live on the flowers, pollen and young fruit. The multitude of early summer invertebrates are in turn forage for numerous resident and migrating birds, and the abundant foliage will provide safe nesting habitat.   

Buckeye flowers and other parts of the tree have toxins that our native bees and other insects are immune to. But the European honeybee isn't, and beekeepers maintain their hives at a distance.

Early in the year, when the toxin level is low, deer and other mammals will nibble young leaves and shoots but avoid mature growth. Then, when the leaves yellow and fall to the ground, they lose the toxins and are once again high-protein food for others.

The seeds—big glossy “bucks eyes” that emerge from their husks in

the fall—are the largest of any California native plant (and very poisonous).