treeblog - All posts tagged: plane

Late summer; a summery resurgence. A hot day, a beautiful clear blue sky. A river: the Ouse in York. A riverside, an avenue of London planes. An icecream, a flake. The sun through the leaves, the sunlight plays on the water. Late summer perfection.

London planes are a common sight in cities, being planted for their high tolerance of air pollution and soil compaction.

Sycamore in Britain: native or non-native?

Sunny young sycamore leaves from a walk up Blackford Hill, Edinburgh, on the 3rd of May 2007.

Sycamore (Acer pseudoplatanus L.) is a large deciduous tree common throughout the British Isles. It may be known in Scotland as the plane. Foreign readers of this blog should not confuse the British sycamore, with which I am concerned, with different species growing around the world which are also commonly called sycamore or plane.

The popular view is that sycamore is not a native of Britain. However, I recently read an article from a 1987 issue of the Quarterly Journal of Forestry by Esmond Harris ¹, who puts forward a case for sycamore being a British native.

Harris begins with a little digression. The English used to call sycamore “the great maple” or the “mock plane tree”, and in fact the taxonomic name means maple (Acer) masquerading (pseudo) as a plane (platanus), as sycamore leaves are similar to those of planes such as the London plane (Platanus x hispanica) and the Oriental plane (Platanus orientalis). Harris writes that the modern common name “seems to have come from monks returning to Europe who saw its similarity to “sycomorus” of the Bible which is the sycamore fig (Figus sycomorus) of the Middle East”.

Back on the topic of sycamore’s provenance, Harris states the popular view is the tree was introduced to Britain by the Romans, but disputes this by arguing that there is no evidence for this “and anyway, why should they introduce a tree for which they would have no apparent use?” The Romans are known to have introduced useful trees, such as the sweet chestnut (Castanea sativa), which was grown for its nuts.

Harris dismisses the theory that sycamore was introduced from France in the Middle Ages on the grounds that, even though many writers have referred to this, none provided any evidence. Sycamore’s natural distribution in France does not reach the English Channel, a fact, Harris writes, used to support the non-native theory. Further support for this theory comes from the lack of sycamore pollen in ancient deposits, although Harris argues that sycamore pollen being gelatinous, it “could not be expected to preserve well” compared with “the hard pollen grain of most trees and shrubs”.

“However, with no positive evidence for introduction” Harris writes, “my own view is that sycamore may well be a native because it grows so well all over Britain, even in the most inhospitable places, and regenerates so freely.” I think this is a rather shaky foundation on which to base a theory of British nativity, for there are known introduced species that grow well and regenerate freely all over Britain (e.g. Rhododendron ponticum) while there are also known British natives that are confined to certain localities or habitats (e.g. wild service tree, Sorbus torminalis).

Harris provides examples of references to sycamore from the Middle Ages: a fourteenth century carving of a sycamore leaf in St. Frideswide’s shrine in Christchurch, Oxford; a written record in Turner’s Herbal in 1551; and a mention by Chaucer in Canterbury Tales, written about 1380, who “was a forester himself at one time” ². But if sycamore was introduced by the Romans or during the Middle Ages, then why shouldn’t it appear in carvings or books from this time?

The next piece of evidence Harris uses to try to support his theory is also rather flimsy. “Unfortunately the wood of sycamore is so like maple that it cannot easily be distinguished in old wooden artefacts, furniture and musical instruments, where it is usually referred to as maple anyway. However the native field maple [Acer campestre] is too small to have been a significant timber tree.” Actually field maple can reach a height of 25 m (~80 ft) and a girth (circumference) of 3 m (~10 ft) at breast height ³. According to Wikipedia, Rushforth’s Trees of Britain and Europe ⁴ describes field maple wood as hard and strong and used for furniture and flooring.

Harris’ case for sycamore being native to Britain ends with a whimper. “The question needs to be asked, “what is the positive evidence that sycamore is an exotic in Britain?” After all, it is the only supposed non-native for which there is no evidence of introduction. We know how all the other introduced trees came here.” Not knowing how sycamore was introduced is no argument for saying that it wasn’t introduced! The rest of the article is rather interesting and goes on to describe the growth of sycamore in Britain, and its usefulness in terms of timber, amenity, shelter, and biodiversity.

Harris didn’t manage to convince me that sycamore is a British native. I’m sticking with the popular view that it is an introduced species, albeit a fully naturalised one nowadays. From the Royal Forestry Society of England, Wales and Northern Ireland’s site:

[Sycamore] is not native to Britain. Its real home is high ground in southern and central Europe extending northwards to Paris and east to the Caucasus.

When and who first introduced sycamore to Britain is uncertain. It may have been the Romans but it was still scarce here in the 16th century and has only really become established over the last 200 years.

As an epilogue to Harris’s article, there was a response by M. P. Denne ⁵ (of the Department of Forestry and Wood Science, University College of North Wales) published in the next but one issue of the Quarterly Journal of Forestry. Denne writes that she has “not yet found any sycamore amongst the fragments of charcoal that I have been asked to identify from a number of Neolithic sites in North Wales”. The second half of her letter is a good response to Harris, so I’ll give Denne the last say in this matter.

Judging from the uses they seem to have made of the different timbers on these sites, Neolithic people must have had considerable knowledge of the wood properties of different tree species. Since sycamore can produce good quality timber on a wide variety of sites, and the wood is strong and easy to work, one would have expected it to have been in frequent use if it had been widely available at the time. As Esmond Harris points out, sycamore regenerates freely and grows well all over Britain, even on inhospitable sites. So if it was native to Britain, is there any reason why it might have been relatively rare in Neolithic times?

¹ Harris, E. (1987) The Case for Sycamore. Quarterly Journal of Forestry, 81 (1), 32-36.
² According to Wikipedia, “on 22 June, [Chaucer] began as deputy forester in the royal forest of North Petherton, Somerset”.
³ Mitchell, A. (1978). Trees of Britain & Northern Europe. Collins Field Guide, HarperCollinsPublishers.
⁴ Rushforth, K. (1999). Trees of Britain and Europe. Collins.
⁵ Denne, M. P. (1987). Is Sycamore Native to Britain? (Correspondence). Quarterly Journal of Forestry, 81 (2), 201.

Red Rose (27th July 2007)

The Plane Tree of Hippocrates

On the Greek island of Kos, an ancient plane tree occupies Platanou Square in the capital, Kos Town. Located close to the harbour and the Castle of the Knights, it is under this plane tree that Hippocrates, oft regarded as the 'Father of Medicine', is according to legend said to have taught many of his students some 2400 years ago. Another legend tells of St Paul the Apostle standing beneath the plane tree, speaking to the inhabitants of Kos and spreading the word of Christianity. According to Wikipedia its crown has a diameter of about 12 metres, which is currently supported by a cage of green-painted metal.

Contrary to the legends, the current tree is almost certainly not as old as they require. Yet it is likely that this tree is a descendant of the original tree, or perhaps a new tree that grew from the still-living roots of the original tree once its above-ground parts had expired. Thomas Pakenham, in his Remarkable Trees of the World (2002, Weidenfield & Nicolson), writes:

For centuries people have believed that this is the tree under which the great healer sat when he taught medicine to his disciples in the 5th century BC. I would like nothing more than to share their faith. [...] But kill-joys will point out that the wood of the oriental plane tree, Platanus orientalis, rots relatively quickly. Today the main trunk is a hollow shell like an old gourd. True, there are large branches growing out of the cage from the east side of the gourd; and there is a new trunk, layered from a branch on the west side about a century ago, now forming a delightful dome of young branches. But I doubt whether the original tree, whose trunk is now a shell, is older than 600 or 700 years.

But wait, say the fans of the great healer. Suppose there was a plane tree there in Hippocrates' day. Of course, it didn't live 2500 years. But its roots did. [...] The trunk, this old gourd, may be the fourth generation of the great healer's trees sprung from the roots.

I have visited the Plane Tree of Hippocrates twice; in August 2004 and again in June 2006. I must confess to being disappointed upon first seeing it, after hearing rumours of this legendary, ancient tree. But after visiting it for a second time, I could imagine its true size, as if its hollow trunk was still solid and whole.

plane

London planes by the riverside, York

Sycamore in Britain: native or non-native?

Red Rose (27th July 2007)

The Plane Tree of Hippocrates

plane

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