The querkleyhew (Querculus arrigiosus) is the pride of the tree-lined avenues of London. It sheds its boughs wherever they extend more than a few yards from the trunk, and at a certain height, the upthrusting members terminate themselves similarly. The exposed wounds heal into lumpy nodules that host nitrogen-fixing bacteria. It is the only tree known to do this. Every spring it grows clusters of thin shoots from these terminations, shedding them in autumn.
The nodules exude resins which are harvested for use in incense. In former times they were also, by the mediaeval doctrine of signatures, favoured as a salve for amputees. The shoots would be gathered by basketmakers and woven into charms against wounds in battle.
The uninformed mistake this curious habit of growth for over-zealous pruning.
Image: Quercleyhews on London streets, not far from the Tate Britain gallery.