Sunday, 24 November 2013

Tree Identification № 1: Liquidambar styraciflua or Sweet Gum

Liquidambar styraciflua grows happily in the UK but it's not a native tree. It comes from the southeastern United States, its range stretching roughly from southwestern Connecticut to mid-Florida and then west towards Illinois, southern Missouri and eastern Texas. And it doesn't grow up mountains except in Central America and Mexico where it seems to be part of the cloud forest. That would be fun to see.

The tree was introduced into Europe in 1681 by a missionary plant collector called John Bannister and first grown in the gardens of Fulham Palace, home to Henry Compton the Bishop of London. Bishop Henry seems to have been a really keen gardener and the 17th century was an exciting time with all sorts of new species making their way to Europe. The first time his new Liquidambar produced its fabulous autumn colour must have been a real thrill for him.

The Liquidambar has bright green hand-shaped leaves which have a lemony scent if you rub them between finger and thumb. And because the leaves are hand-shaped it is often confused with a Maple. Maples too (the best known Maples at any rate) have hand-shaped leaves and sometimes it's hard for the beginner to tell these trees apart.

Liquidambar leaves grow alternately on the twig. Maple leaves grow in pairs, opposite each other. These trees also have completely different flowers and fruits, and bark, but the alternate/opposite twigs and leaves thing is the most obvious when you get close enough to look. And Maple leaves don't have that smell so if you aren't sure, give them a squeeze.

Liquidambars have strange corky wings on the twig, sort of edgewise plates of bark. Quite difficult to photograph.

This particular tree was planted on Willifield Green in 1997 to celebrate the 90th anniversary of the founding of Hampstead Garden Suburb. Léonie Stephen who was then Chairman of the Residents Association planted it using Dame Henrietta Barnett's ceremonial spade. 

You can see here that the leaves and twigs don't grow in pairs and so this cannot be a Maple.


We had more sunshine and blue skies in autumn 2010 when I took these three photos. Liquidambar autumn colour can be absolutely stunning with some trees producing yellow, orange and dark red leaves all at once. Other trees restrict themselves to just one colour. I don't know why.

Liquidambars were not originally used as street trees in the Suburb. But when the Red Oaks planted in a short stretch of Hill Top became simply too huge for their position, it was agreed that the Oaks would gradually be replaced with Liquidambars. Which don't grow quite so large, and what's more, although their leaves are full of tannin, they still break down faster than Red Oak leaves do. This is a bonus for residents used to seeing their street and garden fill up with fallen leaves very slow to biodegrade. Red Oak leaves take forever to break down.

© female flower
I had to pinch this image of the female flower from a Taiwanese website as I don't have any photographs I've taken myself; they are quite tiny, 10mm, and hard to see. This flower is actually from the Formosa Sweet Gum but the flowers are very similar. There are male flowers too (in clusters but even smaller) on the same plant and together they produce fruits like this:

© fruit
So if you still find yourself muddling Maples with Liquidambars check out the flowers and fruits which are completely different from what you expect from a Maple.

It's a really handsome tree with great autumn colour. You need a big garden or a park to get the best from it. If I had a large enough garden (not very likely) I'd certainly plant one.

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