Signs of Spring 9: Sycamore Trees

Photo by Dwspig2, Wikimedia Commons

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The Ohio State University campus is a beautiful place to walk and wander, and I did a lot of each back when I did my Master’s degree there. One place on campus that I loved to go was south of the Oval down in a shady hollow near a pair of old and venerable sycamore trees. The trees had short, thick trunks that were five or six feet in diameter at chest height. The trunks branched four or five feet up into thick sets of spreading branches.  There was a bench nearby where on nice days in the spring and summer I would eat my bagged lunch and read something that was not related to ecology or soil science. I imprinted on these sycamores and felt very at home in their presence.

I found our recently that these trees went through an existential crisis back in 2010! They were marked to be cut down in order to build a temporary construction road for the expansion of the nearby medical center. Fortunately, I was not the only person who valued these trees! A group of Ohio State employees gathered 1500 signatures on a petition to save them, and the president of the university eventually agreed to revise the building plans. This crisis and petition led to the formation of OSU Campus Tree Inventory and the eventual certification of the campus as one of the  Arbor Day Foundation’s “Tree Campus USA” sites.

A lot of good, then, came from this very near destruction of these two hundred year old trees!

Pinchot Sycamore, Simsbury, CT. Photo by Msact, Wikimedia Commons

Sycamores are primarily trees of the forest rather than the city. You see sycamores alongside streams and creeks or on the slopes of ridges where seeps and springs make the ground wet for a good part of the year. In fact, European settlers looked for the distinct colors of the sycamore’s bark in order to locate springs from which they could draw potable water.

In the uncut North American forest sycamores lived for 700 or 800 years and attained great girths if not particularly spectacular heights. Many of these trees had trunks that were  14 or 15 feet in diameter. George Washington described a pair of sycamores in his diary when he was in the Ohio Valley in 1770. One was just shy of 45 feet in circumference (just over 14 feet in diameter)  and the other was just over 31 feet in circumference (about 10 feet in diameter).

Currently, the largest sycamore in the Eastern United States is growing in Ashland, Ohio. It is 129 feet tall with a 15 foot diameter and a 48 ½ foot circumference. It is a true giant even compared to the sycamores described by the early explorers of North America!

Photo by T. Mues, Flickr

A very interesting aspect of these old sycamores is that they tend to rot out their heartwood while maintaining a strong, outer, living wood shell. This forms cave-like hollows at the ground level and chimney-like cylinders up in the crowns. Many European settlers took advantage of these “sycamore caves” and lived in them sometimes for several years until they had amassed sufficient resources to build a cabin. There is a delightful essay about the American sycamore and early North American settlement in Luke Bauserman’s “The Weekly Holler” (January 15, 2017).

Many birds used the upper hollows of the sycamore trunks as sheltered locations for their night roosts and nests. In fact, it is likely that these sycamore “chimneys” were the prime nesting and roosting habitat for the chimney swift prior to the European colonization of North America. The European settlers brought  many things to North America and took away many others, but their chimneys were of great importance to the vertically roosting and nesting swifts especially after the large hollow trees of the “settled” forests were cut down to make way for a more agriculturally oriented existence.

London plane trees in Wadsworth Park. Photo by P. Halling. Geograph

The wild American sycamore has a human created (or at least human facilitated), urban doppelganger called the London planetree. The creation of this hybrid is somewhat shrouded in mystery and many silvics books and websites offer only vague hypotheses about when and where exactly the London planetree came into existence. There are a few forestry historians, though, who have pulled together some very logical ideas about the origin of this “other” sycamore.

The trade in exotic plants from North America began almost immediately upon the discovery and initial exploration of the continent. Avid gardeners in England and throughout Europe imported and planted North American plant species (including the American sycamore) side by side with native plant species and also many other exotic species from around the world.

Ben Venables in his 2015 essay on the London planetree in the web magazine The Londonist contends that John Tredescant planted both the American sycamore and the Oriental planetree in Vauxhall Garden in Kensington (London) in the early part of the 17^th Century. These trees, then, by the mid-1600’s had cross-pollinated and self-hybridized to create the London planetree.

Van Gogh’s “Road Meanders at St. Remy.” Public Domain

The vigor and heartiness of the hybrid was quickly recognized. Its ability to grow and flourish in the soil and space-stressed confines of the city, and its ability to tolerate the often toxic air pollution of an urban environment made it an ideal choice for street-side and urban park planting. Over half of the city trees in London are London planetrees and many European cities (including Paris, Prague and Vienna) have extensive stands of London planes along their beautiful boulevards. Smaller cities also planted London planetrees as is reflected in a famous painting by Vincent Van Gogh entitled “The Road Meanders at Saint-Remy” (1889), a painting that is sometimes referred to as “The Large Plane Trees.”

Historical photo of Apollo Iron and Steelworks housing, Vandergrift, PA, Public Domain

Here in Western Pennsylvania many towns have London planetrees. Nearby Vandergrift, PA (a town designed by Frederick Law Olmsted) has a beautiful set along its curving streets. There are also some large London planetrees along Pittsburgh’s Allegheny River Boulevard. These trees lean out and over the roadway in a very disconcerting manner as they grow toward the limited sunlight  in the shady valley of the Allegheny River.

Sycamore on Rock Furnace Trail. Photo by D. Sillman

There are few simple ways to tell American sycamores and London planetrees apart. The most obvious, to me, is their bark. Both have patchy, peeling bark of white, brown, green and gray that easily distinguishes these trees from all of the other types of trees around them. The London planetree, though, has this type of bark all the way from ground level to high up into its branches. The American sycamore, on the other hand, has dark brown, deeply furrowed bark on its lower trunk and only displays the “sycamore bark” on its upper trunk and branches. Their leaves are different, too. American sycamores have large leaves that have a vague maple-tree appearance to them. They are broadly ovate with 3 or 5 shallow lobes and wavy edges with scattered teeth. The London planetree also has large leaves, but they are more deeply divided into 3 to 5 lobes with smooth edges and few teeth. The fruits of these trees are similar in appearance (brown, somewhat fuzzy balls that stay on the tree through most of the winter), but the American sycamore usually has single balls hanging from its branches while in the London planetree the balls are usually in pairs.

A number of tree guides stress that location is also a good way to tell the American sycamore from the London planetree. A sycamore-like tree growing in a city or town is likely to be a London planetree while one growing along a hiking trail or in the woods is likely to be an American sycamore.