Tree Talk: The American sycamore’s famous offspring

Hang out for long with serious gardeners, and at some point a debate will erupt around a newly introduced plant: Which is better, the species (the parent) or the hybrid? Purists will most often say the species. It’s just in their DNA.

In the early 1970s, when my thumbs were not truly green but I was, the legendary Betty Miller, obviously attempting to take my measure as a plantsman, pounced on me with a question: “Which do you prefer, hybrids or species.”

It was May in her famous Highlands garden. We were looking at rhododendrons in bloom. New to the Pacific Northwest and dazzled by the gigantic blooms and popsicle colors of rhodys, I said I found the hybrids impressive.

“So!” She scorned, “you like cabbages!” I shook in my Birkenstocks and have never been quite the same. Now, I always look critically at any newly introduced plant and ask myself, “Is this really an improvement over nature?”

A few weeks ago I was walking on Madison Street toward the lake. I’d crossed to the south side at Bert’s to enjoy the massive and handsomely mottled trunks and canopy of the London plane trees (Platanus x acerifolia) that line the sidewalk between 41st Avenue East and 42nd on that side of the street. You can also see a line of these stately giants just as you enter the UW Arboretum from the south end. They tower along the east side of the drive between Madison Street and the Stone Cottage. The origins of the London plane tree are murky. It is considered to be a natural hybrid between the Oriental sycamore (P. orientalis) and the American sycamore (P. occidentalis).

According to most sources, the two species were planted in the London garden of English naturalist John Tradescant (circa 1570 to 1638). Both plants had been collected and were growing. A romance developed, they cross pollinated (these things happen) and the hybrid London plane tree was born. Scottish botanist William Aiton (1731-1793) was appointed director of the newly established Royal Botanic Gardens at Kew in 1759. Aiton first mentions the tree in his publication “Hortus Kewensis” in 1789.

The tree had a near symmetrical form; it would eventually stretch up to a height of 120 feet. Its large three- to five-lobed leaves are the size of a human hand, rich green. Ball-shaped bristly seed clusters dangle from stems, hanging on the branches well into winter after this deciduous tree has defoliated. The old bark peels off throughout the year, exposing shining new bark beneath in shades of cream, green (pea, jade and celadon), silvery gray and brown (sometimes rusty). The bark is beautiful and often the subject of close-up, tightly framed photographs. The overall effect is that of looking at a Paul Horiuchi collage.

The plane tree was immediately planted all over London, where it proved to stand up to the infamous coal smog of the capital. The tree’s popularity was rock star meteoric, spreading throughout the United Kingdom and on into northern Europe. In France it was popular because it responded quite well to pollarding. This is the practice of annually cutting all limbs off, down to a nub of a trunk, then allowing the new switches to shoot out in spring like gigantic bouquets, only to be cut off completely,at the end of the following winter. In my opinion, this is horticultural torture, ugly in all seasons. Confront a French gardener with this opinion, and they will likely shrug and, in an annoying, nonchalant tone, mutter “C’est la vie.” 

Following its rambunctious spread in Europe, the London plane tree crossed The Pond, likely in the early to mid-19th century to be greeted by fawning American garden designers like a visit by Victoria herself. “Ah… isn’t she exquisite!” No.

I was thinking about all this as I strolled down Madison under those venerable trees, but I was also feeling slightly petulant. Cognitive dissonance had reared its perplexing head.

I’d just come back from three weeks in western Ohio, where I was born and grew up. There, I’d walked the banks of wide muddy rivers and listened to the singing insects, the chirping birds, the rustle of wind in the leaves and the low groan of swaying limbs. It’s heavenly, right down to the slightly musty scent of the earth and the lilting aroma of the grasses.

I was reconnected with my Huckleberry Finn childhood, and soaring up here and there among the natural arboretum of hardwoods were American sycamores. Their limbs were snow white, the branching pattern was irregular, artistically so. To see them, as they stretch up and out through the dark green foliage of lower growers into a bluer-than-blue sky is like watching a dance by Martha Graham. Rosemary Verey would proclaim them “rhapsodic.” They would make Edward Weston and Ansel Adams break out their cameras. I could go on. I’ll stop now, but, like pork roast with mashed potatoes and sauerkraut, I love this tree. It’s comfort food for the soul.

So, the big question: American Sycamore or London plane tree — which is better, the hybrid or the species?

Well, I’d love to see American sycamores scattered here and there throughout our parks, piercing our silvery gray winter skies with their bold white lines. Yet, those massive trunks along Madison Street with their huge, yet unobtrusive limbs and density of foliage make for city trees that are as good as street trees get. They are proof that our village is old and anchored.

Alas, I cannot pick a favorite. It boils down to the right plant for the right place. In the rich, perpetually damp alluvial soil of Midwestern valleys, I want to see the breathtaking, albeit often unruly, beauty of the American sycamore. Along our streets, the London plane. No “best” needed, really. There’s a right place for about everything.

So, back to Betty Miller, whom I grew to admire immeasurably and who became a friend. Had I been the target of her zinger, today, the current me would have responded not with quaking limbs and a sense of shame for being stupid.

No, I’d have said this: “I love them all. Certainly the purity of the species is to be honored and celebrated. Hybrids can create an altogether different thing. Each has its virtues. As for cabbages, they’re beautiful too. Quite delicious, by the way, and the source of sauerkraut.”