Gwennie supplied the answer.
Gwennie’s first message suggested these beautiful trees belong to the genus Platanus.
That much I had surmised from my field guides to trees and internet searching. But which one? I wasn’t finding a species or cultivar with these strange, knobby branches!
I had narrowed it down to something akin to the American Sycamore Platanus occidentalis, the London Planetree, Platanus x acerifolia, or the Oriental Planetree Platanus orientalis.
But what hybrid or cultivar? Nothing seemed to quite fit exactly.
But then Gwennie supplied the answer, as of course a European gardener would: these trees have been pollarded.
Of course! And the clues were all there.
To pollard a tree is an ancient practice.
Like coppicing, one cuts back the new growth on a regular schedule to shape and train a tree, to maintain its size, or to harvest its wood.
Unlike coppicing, where one may cut the tree or shrub back to the ground; pollarding leaves the basic framework of the tree in place, and simply cuts back new growth to a given point.
This may be done annually, or once every several years depending on the gardener’s needs.
In England, where much of the old growth forest was harvested for building, the practice of pollarding was practiced to grow and harvest wood for building fences and other useful things, without killing the tree.
Some farmers would feed pruned branches and leaves to livestock, others used it for construction or even firewood.
And here is this quintessentially European practice demonstrated in Colonial Williamsburg!
Pollarding trees is a common practice in many European cities- less so in large American cities.
This pruning technique keeps the overall size of the tree in check. But it also makes the tree much stronger and safer.
By limiting the growth of branches, those which remain grow larger and stronger.
Wind moves through the tree easily, reducing storm damage.
Pollarded trees are far less likely to fall in a storm because their reduced canopy won’t resist the wind in the same way a large, unpruned tree will catch the wind in its branches, much like a sail.
We decided to severely prune several large trees in our own garden last summer. Strong winds in a summer thunderstorm took down three huge old oak trees quite unexpectedly. They fell towards the street, but we could plainly see what might have happened had they fallen in a different direction….
The decision was a hard one for me to accept, but it was pointed out, by my very practical partner and his arborist allies, that this severe pruning would protect both the trees, and our home.
And so they cut. And cut; and chipped up beautiful branches full of new summer leaves.
It was so painful to watch, and yet I realized that with the strange storms blowing across the planet these days it was absolutely necessary.
Although July is the wrong time for such an operation (if we thought we could, we would have waited for November) we had the work done, and then hoped for the best.
And all of our trees now show new, vigorous growth.
Not only have they survived their pruning ordeal, they are bouncing back.
It just shows the incredible resilience of established trees.
In fact, one use of pollard style pruning is to maintain trees in a more juvenile state.
Rather than allowing them to mature and establish huge canopies, one keeps them lean. (This reminds me of the longevity diet plans which claim to extend human life through under-consumption of food, and maintaining a very lean weight. Please don’t ask when I plan to get serious with this approach….)
There are some very very old, and very contorted trees in parts of the colonial district, which have intrigued me. They are mostly hollow, and more sculpture than tree.
It seems that one of the effects of continual pollarding is to eventually create a very old tree with a hollow trunk. Now I’m keen to re-visit these old trees, and see if they can be identified by their leaves.
Pollarding isn’t reserved to just Platanus species. It is also used with many broadleaf deciduous trees, including beech, oak, redbud, Malus, Cornus, Acer, Salix, and others. (More on Crepe-Murder here.)
This pruning practice is also used to control Wisteria, Lonicera, and Clematis vines.
Wherever a steady supply of new growth is desired, pollarding can be practiced to increase the supply of flowers, juvenile foliage, and new growth wood.
I am still not positive about the identification of these Platanus trees.
While they resemble our native American Sycamore trees, a case can be made to identify them more properly as Platanus x acerifolia “Bloodgood.” Also known as the London planetree, or hybrid plane, this hybrid claims both the American Sycamore and the oriental plane as parents.
This naturally occurring hybrid first turned up as seedlings in Spain in the 17th Century. Beautiful, strong, and disease resistant, Platanus x acerifolia went into the nursery trade early on and is the preferred Platanus for urban plantings. Not only does the hybrid withstand heat, drought, soil compaction, and pollution, but it has superior resistance to the anthracnose virus.
So, while not sure of the exact species or cultivar, we will agree that these lovely trees are Platanus, some variety of Sycamore or Plane trees.
And they are living works of art. Lovely in all seasons, sturdy and useful; they inspired me to learn a bit more about them.
And with Gwennie’s assistance, a new understanding of tree cultivation has opened up.
All photos by Woodland Gnome 2013-2014