February Tree of the Month-Sycamore

The brilliant contrast of crisp white branches against a deep, true-blue sky is one thing that endears the sycamore (Platanus occidentalis) to many. Sycamores can grow to be giants among their neighboring trees in parks, along streets, or in their native habitat in lowlands or near rivers and streams. Reaching heights over 100’, it would stand out, regardless of the bark color.

But that satiny-smooth inner bark doesn’t start that way. It takes years for the brownish-gray mottled outer bark to flake off and even the most mature trees usually keep the outer bark on the lower half of the trunk. The after-effects of all that peeling bark are messy and can lead to unnecessary concern from worried homeowners about a dying tree or premature removal just because of the annual mess. Michael Dirr, who wrote the ‘Tree-Geek’ bible, says not to plant sycamore because it gets too big and messy for the average homeowner. If it’s not the bark, it’s the leaves or the fruit, leading to a year-round clean-up schedule. Being prone to anthracnose and the accompanying premature leaf drop only adds to the long list of ownership woes.

*Exfoliated bark surrounding a sycamore.*

However, the tree has merits besides being a pretty, yet high-maintenance, face. Prone to hollow cavities, they are used by mammals, chimney swifts, tree swallows, and are preferred for great blue heron rookeries.

Hollow cavities are common in sycamores.

Sycamores can tolerate poor soils, moist soils or anaerobic conditions like a champ. They also take abuse and heavy pruning. Sounds like the typical street tree lifestyle? This leads us to the cross found in London with Platanus orientalis, that resulted in the London plane tree. (Platanus x acerifolia) With records dating back to the 1600s, plane trees have a long history as street trees on both sides of the Pond, notably in London and NYC-where plane trees are the number one planted street tree. The newly renovated Gateway Arch grounds are host to 800 ‘Bloodgood’ London plane trees along the allées. (Amid much controversy.)

Being so closely related, plane trees are easily confused with sycamores. Some people use the two names interchangeably for both or have never even heard of London plane trees and mistakenly call them sycamores. The differences are only easy to spot with close inspection of leaf shape, or fruits. Native sycamores typically have one fruit per peduncle (stem), and London planes have two or more fruits. The round fruits look almost identical for both trees, being a golf-ball-sized brown sphere that disintegrates into fuzzy little individual seeds. Plane tree leaves resemble a maple leaf, with deeper lobes- hence the specific epithet, acerifolia, meaning maple-like leaf. The theory that plane trees have a greener bark tint isn’t always reliable as an ID feature.