BARKING BOTANY

Bark (this is a photo of a cork oak trunk, Quercus suber) holds much botanical fascination and is worth a careful look. Cork oaks are famous for their bark and will grow in Britain in milder areas (hardiness zone 8 for horticulturalists) but are not native: they occur naturally in south-west Europe and north-west Africa and are commercially cultivated, especially in Portugal. 

The great thickness of cork bark protects the trees against forest fires which are frequent in their native lands, but all trees have bark in a great range of forms and appearance. It helps protect them from herbivores, including insects, and the extremes of weather. On a winter walk through our parks and open spaces, it is fascinating to observe the different tree trunks. Trees have a central core of vascular cells which carry water and nutrients to the leaves from the roots. This is the cambium, the outer cells of which become compressed as the tree grows, then die off to leave a hard layer of lignin and cellulose which we know as the bark and which protects the tree. I have simplified this but that is the essence of it. For technical botanical detail, there is information for example at https://bit.ly/barkstructure.

The range of colours and forms of bark in our native and garden trees is amazing, and you can often identify a tree in winter just be looking at its trunk. Some are immediately recognizable, an example being the London plane Platanus x hispanica, which is familiar to most of us, or perhaps the soft bark of the wellingtonia Sequoiadendron giganteum. You can find all sorts of small invertebrates hiding under the flaky bark of a London plane, and children seem to be endlessly fascinated in being able to punch the bark of a mature wellingtonia! Here is a selection of bark pictures of some native and exotic garden or street trees to look out for, but of course there are dozens of others to observe and enjoy.

Betts Ecology have a wide range of native and exotic trees on our sites and we record both the species and their condition. If you find one with unusual bark which you don’t recognize and can’t identify, do let us know (with a photo). 

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