Maryland has been my home for 30 years, most of which I’ve spent under the canopy of an enormous tree. It is a gnarly, lumpy beast with a trunk five feet across that splits off into massive limbs large enough to be trees in their own right. Buried deep in one of those is a cable – attached, we suppose, sometime back in the 1940’s or 50’s – that still anchors all of the utility poles on our street. It is a tree whose impressive presence is so central to our local landscape that I can’t imagine living here without it.
The gigantic tree was one of the first features that attracted me to this property. My first glimpse of its patchy, camouflage-patterned bark, scalloped leaves, and furry round seed balls told me its name immediately: sycamore. The tree’s behavior confirmed this. In summer, it litters the yard with ragged strips of shed bark: sycamore. The brittle, irregular limbs grow quickly and are prone to breaking, often getting hung up in the crown: sycamore. Small branches sprout from the base or at random spots along the trunk: sycamore. One of my neighbors up the street refers to this and other trees like it in our neighborhood as “London plane trees.” I always dismissed this as Maryland vernacular for sycamore.
Last week, the Maryland Biodiversity Project announced a “Facebook Blitz” to document sycamores throughout Maryland. There was plenty of cautionary instruction about making sure that a tree was really an American sycamore. Wild American sycamores grow almost exclusively along streams. The bark on their trunks is rough, and the branches display the striking camouflage pattern, with a bone-white background. The seed ball fruits grow singly. These are the features, they emphasized, by which one may distinguish the American sycamore from a close look-alike that is often planted in urban settings.
At Jemicy, we found several sycamores growing in their classic habitat, along the banks of the stream, white limbs stretching high into the canopy and standing out against the darker tulip trees and oaks. The rough, dark, lower bark contrasted with the upper limbs, which bore a few single seed balls.
Back at home, I went out to photograph our sycamore as well. As I searched for a good angle to capture the immensity of the tree, I paused to examine its features more closely. The gigantic lower trunk was a lumpy patchwork of colors and peeling layers, but the bark there was not uniformly rough like those trees at school. Its upper branches bore the same palette of colors in greens and yellows – but without the signature stark white base color. To top it off, dangling from some of those branches were last year’s seed balls – paired, not single. This tree, and several others just like it in this dry, upland area, were clearly planted here intentionally. This was not an American sycamore.
My neighbor was right: it appears to be a London plane (Platanus × acerifolia), a hybrid cross between the American sycamore (Platanus occidentalis) and Oriental plane (Platanus orientalis). This species has been planted extensively in urban and suburban settings due to its tolerance for pollution, root compaction, and resistance to diseases that affect the native sycamore.
Does my 29-year-long mistake even matter? The tree certainly doesn’t care. it is just a classic case of assumptions superseding research. I had never heard of a London plane tree before coming here, so I went with what I knew: sycamore. The differences between the two species were never apparent to me, because I wasn’t looking for them. Even when traveling in Italy a few years ago, seeing a row of massive trees in Florence’s Boboli Gardens that looked just like my tree at home, I assumed that they were sycamores.
“Science loves a good mistake!” I often tell my students. This tree that I love has not changed, just because I now know its true identity. In fact, my awareness now prompts me to examine apparent sycamores with a more discerning eye, and to ask new questions about our tree: What caused those odd lumps on the trunk? Does this hybrid share the same pests with American sycamore? Do both species shed minuscule, highly aggravating hairs from their leaves? Why does it have a spring leaf drop? Are its seeds fertile? After all these years, there is new opportunity to learn from the giant in my yard.