This is a shoot growing from an epicormic bud lying beneath the bark of a stem or branch of a tree. The buds lie dormant beneath the bark with their growth suppressed by hormones from active shoots elsewhere within the crown of the tree. Certain conditions can cause these to develop into active shoots, such as when either natural or pruning damage occurs to higher parts of the tree, or light levels are increased following removal of trees nearby. Epicormic buds and shoots occur in many species, and can be quite prolific in certain species such as Lime, Elm and Ash, but are absent from many others, including most conifers.

 

Epicormic shoots are the means by which a tree re-grows after heavy pruning operations such as cyclical pollarding or coppicing, where the tree’s stem or branches are cut back on a regular cycle to maintain size in urban areas or re-generation after timber harvesting. These pruning techniques cannot be used on species which do not possess strong epicormic growth abilities.