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Wednesday, June 29, 2011

Aesculus californica - California Buckeye

The California buckeye is are beautiful native tree. Unlike most members of the genus Aesculus, A. californica blooms after the foliage appears and is often summer deciduous in its native habitat. Reported to be a slow grower, it can put on several feet a year when young if properly cared for. Generally up to 20' but can become larger if near water. With age it develops a great broad spreading dome-shaped canopy. Can be multi-stemmed or with a single stem.

Here is a nice specimen on 17th and East Cliff in the winter.

The foliage is typical of buckeyes (horsechestnuts are the same genus), opposite, palmately compound, with five leaflets, oblong or oblanceolate leaflets, 3-6" long and 1-1/2" or more wide, margins are lightly serrated. Dark green above and lighter below. Often crinkled, or quilt-like due to the deeply set veins. Leaflets can be flat or V-shaped  depending on were the tree is growing, in shade it will be wide and flat, and in the sun it will be V-shaped.  For the most part, smaller than other members of this genus.

They look really nice emerging from the bud in the spring.

Stems are smooth, gray silver colored, terminal buds large. Older stems and bark make this a beautiful tree when leafless. The wrinkles around the base of the branches is an area called the branch collar and is part of the trunk, not the lateral branch. Ideal specimen to see this critical area as its were you want to prune, don't cut into the collar.

Flowers are borne late in the spring after the foliage has emerged. They are whitish pink about 1/2" long in a long raceme about 10" long or so. Stamens are long and showy. There is a "Pink" cultivar in commerce, 'Canyon Pink'. This picture is from Wilder State Park.

Fruit is a typical buckeye or horsechestnut. The husk is smooth, thinner than others in the genus, generally containing one seed but occasionally 2. (There should be 3 but 2 abort during maturation.) They are light brown colored when mature, 2 or so inches long, sort of pear shaped. They are poisonous if eaten raw.

Look like little green apples in the fall hanging in the tree.

In the husk, you can see the lines on the fruit showing the three compartments of the ovary that developed into a fruit.

After all these years of not looking at the young fruit I pulled one down and sliced it open. Obviously three carpels (compartments as seen above) but a bit of a shock, there are multiple young seeds developing.
I was always under the false impression that they only had three ovules and for some reason only one developed (sometimes 2) per fruit. Wonder what causes all the others to stop allowing one dominate seed to mature?

Even the roots are silver-gray in color, beautiful specimen hanging on.....

This is one of my favorite ones in Wilder State Park, love the trunk and the Spanish Moss on the branches.

Bonsai specimen at the SF Flower show. Wish it was in bloom, must be spectacular.

Misidentification: Other members of this genus perhaps. A. pavia might look like it when not flowering as the foliage is small as well.

Corner of Park where it ends at the parking lot for the beach.

Santa Cruz
Wilder State Park,
Entrance to Nisene State Park
17th and East Cliff/Portola Dr.

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