I was very lucky to be invited along to a Friends walk at Stone Lane Gardens this week.
The walk was taken by Paul Bartlett, the Gardens Manager who managed to cram so much fascinating information about birch and alder into his talk, that I couldn’t write it down fast enough.
Birches (of which Stone Lane Gardens hold one of several National Plant Collections, along with Alnus) are fantastically versatile trees. From the sap which is high in sugars and can be used to make syrup and beer; to the wood which is used for making anything from canoes to planes to plywood for skateboards. The bark can be made into shoes and the leaves into tea. Birch bark can also be used as a firelighter (see the photo below), which continues to burn fiercely even when on the damp grass.
Birches are northern trees which means that their leaves drop early to allow the tree to prepare for a long winter. Many of the species grown are from mountainous areas where the winter is colder but they receive a lot more sun in the summer. This enables them to enter winter with riper, and thus more cold-resistant wood. When grown in our milder, cloudier climate the wood often doesn’t harden sufficiently, leading to die-back.
The colour of the bark is probably determined by betulin, a compound that is found in greater amounts in white-barked trees and less in the darker ones. One theory is that it confers a resistance to uv light. The bark peels so attractively to allow the tree to increase in girth. Different trees have different strategies for this, the oak and pine crack, the London poplar flakes its bark.
And of course, the birch is used for ‘birching’ (ouch) and is what you use when you beat the bounds!