I have been meaning to do a post on London plane tree (Platanus x. acerifolia) for a while, now. Being at Bryant Park last Saturday buoyed my enthusiasm for the tree so I am finally posting some photos of Platanus being used to its best effect -- in an allée.
Plane trees don't have a dense canopy which helps create perfectly dappled light beneath their limbs. The exfoliating bark (in sand, green, white and beige) also reflects this light.
In late summer, they do get Anthracnose (not Discula anthracnose, another kind of fungal disease that afflicts dogwoods) and their leaves may drop completely, though this disease's effects are only cosmetic and the following spring the trees recover.
Perhaps one of the most famous uses of a plane tree allée is in Versailles. I once had a wonderful photo of this -- 100 feet high specimens lined a drive on axis with the Apollo fountain -- alas, it seems that I have lost this pictuure in a computer snafu.
Instead, I will post a similar French use in Fontainebleau:
The other thing that makes a plane tree allée enchanting is the way they lean away or into the path. I am not sure why this happens; I could guess that compaction affects the root system, which then affects how the tree is anchored, but it would be an uneducated hypothesis -- to say the least.
Instead, here's a shot of the bark up close (on the left):
Plane trees are closely related to the native sycamore (Platanus occidentalis), though sycamores have larger leaves, a coarser branching habit and the presence of a dark, woody scaly bark that grows around the lower 10 feet of the tree. Above the scales, the exfoliating bark is much whiter. Finally, they set seed in groups of one or two, not two to four. You might recognize a sycamore more easily as they feature prominently in the landscapes of Andrew Wyeth: