Sunday, November 21, 2010

A Tree-Spotter's Guide to Bark: Part 4

The success of London plane Planatus x hispanica as a street tree owes a lot to its propensity to slough off flakes of bark frequently, shedding pollutants along with it - and leaving an attractive abstract pattern of pastel coloured patches.

Marooned in a sea of of concrete and asphalt and assailed by exhaust fumes; it's a small miracle that plane trees like this not only survive but thrive in the urban jungle.
On a sunny day, it's pretty obvious how redwoods got their name. This is the giant sequoia Sequoiadendron giganteum, a species that was introduced into Britain in 1853. The bark is incredibly thick, soft and fibrous and, it is said, has been adopted as a roosting site by treecreepers that hollow out small depressions where they spend the night. Where did treecreepers roost before 1853, I wonder? The tree is sometimes known as Wellingtonia, named after the Duke of Wellington who died the year before it was introduced, but attempts to formalise this name as Wellingtonia gigantea - an act of imperialistic arrogance - upset the Americans. It was, after all, their tree so they countered with the name Washingtonia, to commemorate their national hero.... but there was already a palm species with the same name. Thankfully, it turned out that it was a cousin of the coast redwood Sequoia sempervirens and so could also be called Sequoia, circumventing any further taxonomic squabbling. It became Sequoiadendron in 1939, when detailed examination revealed that it was sufficiently distinct to be placed in a genus of its own. 

Horse chestnut Aesculus hippocastanum becomes flaky with age but isn't easily shed - so it often acquires a veneer of green algae on the northern, shady side of the trunk.
Elder Sambucus nigra rarely lives long enough to develop tree proportions but when it does the deeply fissured corky bark can be very attractive.
When common hawthorn Crataegus monogyna grows as a tree, rather than as a regularly cut hedgerow shrub, it tends to branch from low down from an early age and this produces a trunk that resembles vertical branches welded together - which is what they are, I suppose.

For more information on tree identification click here

9 comments:

  1. I've just stumbled across this blog. Very interesting and I shall work my way through the trees. Brian

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  2. Another fascinating episode, Phil. Many thanks.

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  3. Hi lotusleaf,Adrian,Emma and Toffeeapple, I'm enoying myself tracking down interesting specimens!

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  4. These have been very useful in improving my (very poor) identification skills. Many thanks

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  5. Hi James, to be honest I've focussed on the more distinctive, photogenic species ....

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