The trees of London are a slow-rising tide. Walk across the centre of the city, from Temple Station on the Embankment to King’s Cross on the Euston Road, and you have them with you all the way. Weedy young ginkgos line Arundel Street. In the spring, lilac reaches above the railings of Lincoln’s Inn Fields. In August, the pavement which runs alongside Coram’s Fields playground by the sheep enclosure is black with fruit from the overhanging mulberry. In Judd Street, there are cherries (both wild and cultivated) and more than one species of ash. Limes are not common here, as they are in some other parts of London, where, in summer, they make cars and pavements sticky with falling honey-dew. There are rowans with bright red fruit and spiny Robinias. The total number of species is great, but one dominates: the plane, the tallest, the widest spreading, the noblest of the trees common in London streets, parks and squares.
The green tide is rising because more trees are planted than are cut down – or so it seems to the casual eye – and because few are trimmed to size, fewer than would be the case in France. The height of the tide will depend on taste and on what is often still unknown: the size to which an exotic species grown in this country can reach. Dendrologists must often leave knowledge of the potential size of individual trees to their successors. For example, what appear to be among the very first ginkgos (1758) and London Planes (1680) planted in England are still alive and flourishing. The Wellingtonia – the giant sequoia of California – which was introduced to Britain in 1853 has been known, in its native habitat, to grow to a height of 100 metres, to have a girth of 27 metres and to live for up to 3400 years. I don’t know of any in Central London but Wellingtonias 150 or so years old, and standing taller than other trees, already punctuate many horizons in those parts of England where big-scale landscape gardening has been the fashion.
There have been times, however, when London’s green tide was out. John Evelyn’s intentions in writing Sylva (‘A discourse of forest and the propagation of timber in his majesties dominions’), published in 1664, were practical. The book answered a request from the Commissioners of the Navy to the Royal Society for advice on the management of woodland – timber for ships was in short supply. Evelyn sets out the reason for this in his dedication to the King:
But what shall I then say of our late prodigious Spoilers, whose furious devastation of so many goodly Woods and Forests have left an infamy on their Names and Memories not quickly to be forgotten! I mean our unhappy Usurpers, and injurious Sequestrators; Not here to mention the deplorable necessities of a Gallant and Loyal Gentry, who for their Compositions were (many of them) compell’d to add yet to this Waste . . .
Nor was it here they desisted, when, after the fate of that beautiful Grove under Greenwich Castle, the Royal Walk of Elms in St James’s Park, That living Gallery of aged Trees (as our excellent Poet calls it) was once proposing to the late Council of State to be cut down and sold . . . if my Authority did not rescue those Trees from the Ax, sure I am, my Arguments did abate the edge of it; nor do I ever pass under that Majestical shade but methinks I hear it salute me as once the Hamadryad did the good Rinaldo . . .
These sentiments are not so far from those that inspire people to chain themselves to trees when a bypass is proposed and, for all that Evelyn was producing something close to a Royal Commission report (he conflated information he had got from other fellows of the Society), it is more than literary fashion which leads him so often to quote from poetry or ancient history. Thus the Oriental Plane is the ‘incomparable and shady Platanus, that so beautiful and precious Tree’, which the Romans ‘brought out of the Levant, and cultivated with so much industry and cost, for its stately and proud head only’, and of which Pliny says that there is ‘no Tree whatsoever which so well defends us from the heat of the Sun in Summer; nor that admits it more kindly in Winter’, thereby proving that classical sources give the same reasons as we might for planting a tree whose timber is of no great value and which is the source of no useful by-products.
I pass the London Plane shown here most days as I cross Brunswick Gardens. I am not the only person who is taken with it: when I was making some primitive measurements and taking photographs a couple came up and told me that they felt as I did. I led them astray, however, because although I remembered rightly that Alan Mitchell says in his Field Guide to the Trees of Britain and Northern Europe that the circumference of a tree in inches at five feet above the ground gives a good idea of its age in years, I had forgotten that he also says that planes are an exception and increase at twice that rate. So even if my efforts with a piece of string were accurate, the 21 ft girth translates into 125 not 250 years. But Al Smith, who is in charge of trees for Camden Council, tells me that plane trees in Lincoln’s Inn are reckoned to be 180 years old and that, as these are of a like size, I was, perhaps, less far off than I thought. My attempt to make a hypsometer (the instrument you use to measure the height of trees – they’re now available with laser distance-measuring and built-in electronic calculator) with a protractor and a piece of card gave such an unlikely result that I would rather guess its height – something over 100 feet perhaps.
The origins of the London Plane are mysterious. It is almost certainly a hybrid: the result of a cross which took place somewhere in Spain or Southern France around 1650 between a specimen of the Oriental Plane (Platanus orientalis) – native in South-Eastern Europe and Asia – and the American Plane (Platanus occidentalis). Doubts about parentage and inherent variation mean that it has appeared in the literature under various descriptions: Mitchell, who is punctilious over taxonomy, gives three botanical names (Platanus x hispanica, Platanus x acerifolia and Platanus x hybrida). There are yet more names for varieties, which are not always easy to distinguish, although a website on the botany of plane trees (www.chengappa.demon.co.uk/planes) gives descriptions and pictures which should let you have a go at distinguishing pyramidalis, say, from ‘Augustine Henry’.
The London Plane proved itself, above all, as a town tree. It is tough; its vigour, smooth leaves (which the rain washes clean) and a bark which is renewed by constant flaking make it immune to the effects of filthy air. Soot is no longer a problem but the London Plane is still regularly planted. Its only bad habit is producing hairy seeds and shoots; the tiny fibres irritate the skin and lungs, so tree work is now done in winter. It must be admired in our climate for itself alone: planes, planted in Southern Europe to give shade, are planted in London for magnificence.
You can see how strongly the tide of trees is running when it splashes up against an old building, against the church of St Clement Dane, for example, on an island in the Strand. A year ago the head of Bomber Harris, whose bronze statue stands next to the church, was brushed by the lower foliage of a plane tree. Now his companion, Air Marshal Dowding, is suffering the same indignity. Meanwhile, along Great Russell Street, a row of planes overhangs the high iron railings of the British Museum. They rise, too, over Bloomsbury’s squares and churchyards. If all London’s buildings were suddenly removed, we would find the land to be as well-treed as many country parks.