California Buckeye (Aesculus californica)

The California buckeye (Aesculus californica) is common in the Bay Area but harsh winds, sandy soils, and other factors conspired to prevent very many trees from growing in San Francisco prior to European contact. A Flora of San Francisco, California, published in 1958, states that Archibald Menzies in the 1792 Vancouver Expedition records the buckeye on the “skirts of the Bay and hilly Country behind” in the northeastern part of what is now San Francisco.

The flora reported only one tree extant in the city in 1958 and it is still thriving at the Caltrain station at 22nd and Pennsylvania Streets. Subsequently we have located a sizable one in a backyard at the base of a cliff at the open space at Palou and Phelps Streets. Other large ones are on the shoreline of Mallard Lake in Golden Gate Park and in a front yard at 2694 McAllister Street, corner of Willard.

The trunk of the last-noted one is approximately two feet diameter just above its swollen base. Knobby excrescences and fused branches invite visual inspection, one fusing branch producing a ten-inch-diameter doughnut hole. Some of the limbs are larger than the trunks of most trees you will encounter. An impressively large California bay laurel keeps it close company. But you should see the trees soon-they are growing in front of an old empty cottage with an unkempt yard (as is the cottage next door) and they both have “condo” written all over them. It would be nice if the landowner were enlightened enough to save them but the world isn’t like that, is it?

BuckeyeAre these cited trees indigenous occurrences? Estimating the age of a buckeye is not easy. Buckeyes have a moderate growth rate even when growing in fairly dry surroundings. When water is available growth can be rapid, so that a large tree is not necessarily very old. Buckeyes share with olives the ability to look ancient after only a few decades. In the case of the McAllister tree, reasoning tells you that it is not likely that a buckeye grew atop windswept sand dunes. Lack of water and leaves sensitive to wind would prohibit that. More likely the buckeye and the bay were planted by the owner after the cottage was built. The Mallard Lake tree could be indigenous because it is growing in a depression, out of the wind and where the water table was probably high enough. However, abundant water is provided by the lake and it could have been planted within the last five or six decades.

Buckeyes are easy to grow and if you have space in your yard (they will eventually want to spread thirty feet or more) you might want to pick up a seed at our November plant sale. We recommend seed rather than a plant because a buckeye grows quickly from seed, it will have a better-formed root system, and it will grow faster than if you had started from a plant in a can.

Posted in Gardening with Natives.

Jake Sigg

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