Photo of Bluebell Woods in Sussex Photo of Bluebell Woods in Sussex

What are Elephants’ Toes in Trees?

Elephants’ toes are the nickname for the way the bottom of a tree trunk flares out towards the prevailing wind.

In the video above and photo below we can see the base of the trunks of these London Plane trees flares out more to the left. The prevailing wind in London has come from the southwest, so we can work out that southwest is to the left of these trees.

An explanation of this effect from the book, How to Read a Tree:

If the trunk travelled vertically down into the soil and the roots headed out horizontally from there, it would create a right-angle and a weakness. Whenever the wind blew, there would be huge stresses at this junction. That is why the base of the trunk and the roots meet at a curve just above the ground. It softens and shares the burden of these stresses.

From a little distance we won’t see the roots, but the curve at the base of the trunk is still visible. It is normally more pronounced on one side of the tree – the windward side – so the base of the trunk appears asymmetric. It creates a shape that reminds me of an elephant’s foot, where the elephant’s toes point into wind.

Some species take this logic to extremes and grow ‘buttress’ roots. The junction is replaced by mighty root struts that reach quite far up the tree. Buttress roots are more common in soft, moist ground and the trees that grow there, like poplars, and are widespread in the soggy-soiled tropics.

It’s a strange nickname, but I think it works…

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