It has been estimated that over 50% of the street trees in the capital are London Plane trees. Robust, pollution resistant and able to survive the root compaction that occurs under roads and pavements, they go largely unnoticed, in spite of their enormous size – the largest trees are over 130 feet tall, with trunks ten feet in circumference. They have grown to such a size slowly – they can live to for over two hundred years (Kew has one which was planted in the 1770’s). Many now have an uncomfortably cramped and oversized appearance, like a flamingo in a bird cage.
The bark of the London Plane is one of the reasons for its ability to survive the toxins that it encounters from diesel fumes and atmospheric pollution. The bark of the tree is shed regularly, taking the poison with it, and this leaves the trunk with a paint-by-numbers look – organic shapes of beige and green grey and khaki.
I remember the one and only field trip that we did when I was in primary school. Our class, a bunch of scalliwags and urchins, went across the road to West Ham Park in the East End of London. We were looking at the trees to see whereabouts on the trunk the green algae grew most thickly. After compiling our notes, it was clear that the algae much preferred the north side, and it was the first time that I ever realised that nature was not only interesting, but helpful. Imagine my delight when I looked at the Plane trees on the High Street and saw that exactly the same was true, nearly forty-five years later. Algae is not fond of direct sunlight, and so prefers the shadier side of life, as does moss. The bark above is on the north side of a tree. The picture below shows the south side of the same tree:
Or, for another comparison:
You could find your way by these trees, the green sheen on only one side showing you your true north. There are so many forgotten ways of wayfaring, so many natural maps. Just knowing that the sun rises in the east and sets in the west can help. Knowing that buttercups grow in the wettest places can save you from soaking your plimsolls. Knowing that horseradish grows in pasture grazed by horses can give you an insight into who might possibly be lurking just behind that hedge.
Nature gives us a thousand words to read, but we are mostly illiterate. All that I’ve learned, I’ve learned from those who went before me, my parents and grandmother, and from looking carefully, and from reading books. I know a tiny fragment of what there is to know, but when I find something out I squirrel it away. You never know when it’s going to be useful.
On the other side of the crossroads, the Plane trees have been pollarded.
Young men in safety harnesses pulled themselves up to the top branches and attacked all the little branchlets with a chainsaw a few months ago. To start with, the trees looked ugly and angry, the ends of their branches clenched into fists, like giants performing a war dance. Now, long twigs are starting to appear like thin fingers, and soon there will be leaves, although London plane trees are late to leaf.
These trees have been pollarded every couple of years, for their entire lives. The belief is that limiting the crown will limit the spread of the roots, because this is what the council fears – that the roots will infiltrate their million little rootlets into sewers and into the conduits of telephone lines and electricity cables. They also fear that, uncorrected, the branches will crash down onto passing cars, or take out the windows of double-decker buses. However, the trees are benevolent and respond to their regular mutilation by growing taller and leafier with each passing year.
Plane trees are a blessing in the summer. Their heavy shade cools those who sit underneath them. Trees can reduce the temperature in urban areas by several degrees, simply because they transpire – they pump water vapour into the atmosphere which acts to cool the air.
However, they are also something of an ecological desert. They are not native to the UK, being a hybrid of an American and an Asian plane tree, and so, although crows and squirrels may make an occasional nest or drey in their topmost branches, although woodpigeons may court amongst the new spring leaves, they have few creatures that actually depend on them. Compared to an oak, or an aspen, or an elm, they are sterile – big, leafy, predictable but, in all truth, a little dull.
Some councils have started to replace the Plane trees, as they die, with other species. There are a lot of members of the cherry family, for example, lots of rowan trees. These are much daintier and smaller proportioned, with blossom in the spring, and berries for the birds. It is hard to disagree with the choice, but they are not as hefty as the trees that they replace, and will not provide the same degree of shade and cooling. Plus, history will tell whether they will have the Plane tree’s remarkable resilience. Climate change is making these considerations more and more important.
The big disadvantage of the London Plane is its seeds.
The tree produces spiky seed heads for much of the year, which look like the mace of a medieval knight. The seed heads burst open to reveal thousands of tiny fine seeds, which are implicated in hay fever and asthma. However, in a city as polluted as London (the official air pollution rating for the first part of this week is ten, as high as it can go) it’s always difficult to ascertain whether the reason that people are coughing and wheezing is the pollen or the particulates in the air.
So, the London Plane is a great whale of a tree, massive and mighty. Some of the trees on East Finchley High Street will have been there when it wasn’t cars coming up the hill but horse-drawn coaches, when there was a pig market behind the pub, when an incendiary bomb landed on Temple Road and killed fifty people. We are such temporary creatures, compared to trees.