Foliage Friday: Buckeye Tree

There is a buckeye tree right outside my window. When I moved to Palo Alto last July, this plant made it look like it was late fall. Its leaves were shriveled up.

I was told that this is a California buckeye tree, and that this is normal. Its lifecycle is shifted relative to other trees. It blooms in late winter / early spring and the senesces in mid-summer. Although this lifecycle seems odd, it actually makes sense for a tree specifically adapted to California’s climate. It leafs out in the winter when rain is (slightly) more plentiful and then goes dormant when nary a drop of water falls from the sky. Supposedly, the blooms come in early summer, and it goes dormant almost immediately afterwards, but I have yet to see any blooms myself.

The buckeye fruit (or nuts?), as well as the leaves and bark, are poisonous. Interestingly, the pollen is also toxic to pollinators. I read this on USDA’s forestry database: “Honeybees are the chief pollinators of California buckeye, but the pollen and nectar are toxic to them [5,9,14]. Losses of adult honeybees and their larvae due to poisoning can be severe [9]. Human beings have been poisoned by eating honey made from California buckeye [18].” Crazy, right?! What kind of a plant would kill its own pollinators?

After doing a little more research, it sounds like the buckeye is poisonous to honeybees, which are not native the US, but the buckeye might not be poisonous to native bees and other pollinators. Native bees must have evolved alongside the California buckeye to be resistant to its toxin, I suppose…who knows?

The blooms look like this:

Image from: Pacific Horticulture

I’ve been keeping my eye on the tree, watching it leaf out, and waiting for the blooms. The leaves have kind of a quirky look to them.

Here it was in early January….


….late January….

Small leaf buds

…still late January….

Leaves are looking like small pineapples


Chartreuse umbrellas


Deeper green leaves

…and that’s where we’re at. Still waiting to see those blooms… and I’ll be sure to warn the (non-native) bees not to go near them!

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