Tuesday, 2 July 2013

A New Approach To An Old Favourite

One of my favourite specimens here at Westonbirt is this fantastic oriental plane, Platanus orientalis, photographed below.

It is found alongside Main Drive in the Old Arboretum and following the installation of a new path, linking this ride and Mitchell Drive, it can now be appreciated from a new angle (if you've stuck to the paths in the past, that is!). Growing on the corner of what is now a crossroads, the older routes passing the tree can bring you almost underneath it before you realise quite how magnificent a specimen it is, whereas the new path offers an unimpeded view as you approach, affording a golden opportunity to appreciate the sheer awesomeness of this tree. 

Taken in the sunshine yesterday, the photo does not do the tree justice at all.
You shall have to visit it yourselves!

Native to south eastern Europe, the species has been cultivated here since the 16th century and there are many venerable specimens both in this country and across Europe, with trees being aged at over 1000 years old. Locally, there is one of incredible stature south of Westonbirt at Corsham Court, near Chippenham, which is reputedly the tree with the largest spread in the U.K, averaging around 200 feet. Having been planted in 1757, this tree is a mere youngster and as is characteristic of many specimens, it has layered, rooting down and forming new stems, which have grown up and out, broadening the overall spread considerably (unfortunately I have no photos of this one - I shall have to pay another visit! For interest, there is also a sizeable black walnut, Juglans nigra, just to one side, and is being somewhat consumed by the plane!). Another at Westonbirt has layered similarly, and given the chance (and time!) would no doubt compete for overall spread size!

The specimen photographed above also has the unusual feature of  a 'natural brace' (see photo below). Long ago a branch appears to have grown from one of the major limbs towards another and then fused. It continues to put on secondary growth and provides additional structural support! Unusual but not unheard of, other species seem to have more of a tendency to fuse in the crown, for example the Persian ironwood, Parrotia persica, as can be seen just the other side of the path from this tree!

The 'natural brace', where branches have fused.

One of a few large oriental planes growing with us here, and while this species is the most seen of the Planes at Westonbirt, many people are more familiar with it's hybrid offspring, the London plane, Platanus x hispanica. Adorning many city streets and squares, it's attributes as a tree for the urban environment have long been recognised. Pollution tolerant, its young shoots and leaves are clad with hairs which trap particulates and once mature, these are then washed away by rain, taking any particulates with them. The tree also regularly sheds its bark and in doing so, lenticels that have been blocked by pollution are also shed, exposing fresh ones beneath, allowing continued gas exchange essential to the tree. This flaking bark is another feature and draws particular attention to the form and branching structure of the trees during the winter months. The tree is further suited to urban environments due to its tolerance of poor and compacted soils, and also of severe pruning (an unfortunate yet common occurrence on urban trees).

The form and bark can be strikingly attractive in winter.

However, the tree may not be to everyones taste, as the pollen can cause hay fever (I have seen the air thick with it on days in May in London parks!). Also, the fine hairs of its fruit can cause irritation to the eyes and skin as they disintegrate. Arborists tend not to work on specimens without a dust mask!

The other parent of the hybrid is the western plane or buttonwood, Platanus occidentalis. It is native to Eastern North America, where it is also known as sycamore, which has the potential to cause confusion!!  It doesn't tend to grow well here, with good specimens scarcely seen. There are a further handful of plane species, along with a number of selections of those mentioned above, and all things Platanus can be discovered on this particularly comprehensive website

The view looking back down the new path, towards Mitchell Drive.
Notice the Aesculus indica in flower on the left!

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