Platanus racemosa - California sycamore

What a great looking tree in its native habitat. I love driving thought the valleys where you can see the growing along river beds and bordered by oaks further away from the river. Here is a shot driving from Carmel to Salinas in the winter, when they look better anyway. Trees can reach 100 feet but in landscapes they are in the 40-50 foot range.

The leaves are alternately arranged, simple and palmately lobed. The 5 lobes are narrow and long, much more so than the more common London Plane. Generally 5-8" long and wide the leaves are usually quite hairy when young.

Due to anthracnose this is what they usually look like in early spring. 

An interesting feature on sycamores is the petiole base is swollen to cover the lateral buds. You can also see the stipules in the picture.

Flowers are borne in dense round heads hanging in pendulous chains. They are red in color.

Fruit is an aggregate of achenes, looking like a round small golf ball. The are in clusters of 3 to 7 and hang in long chains. The fruit falls apart on the tree leaving behind a smaller round ball. 

The bark found on most old trees is exceptional. Way more white showing though that on the London Plane Tree. Older trunk like the one below are great. Bark is variable. I have seen 15-20 year old trees with out any exfoliating bark and some with exceptional bark.

This is the one at the base of the hill on Spreckles Drive in Aptos on the way to the flats.

I have heard from reliable sources that the only way to get a true California sycamore is to clone one from a very old one in its native habitat. They hybridize easily with the London Plane tree and all the stock from nurseries more than likely are hybrids.

Misidentification:
Other Sycamores, especially if it happens to be from a nursery. Look for the bark on an old tree but that is not always reliable. Look at the leaves, they have much longer lobes than that of the London Plane tree.

Location:
Aptos
the best place to see london plane and the California Sycamore side by side in a mature landscape is on Sea Cliff Drive E. at the corner of Sea Terrace Way. The condos have 3 sycamores and one london plane tree.