shoot arising from a dormant bud. or from newly formed adventitious tissue.
epicormic shoot (Wikipedia)
An epicormic shoot is a shoot growing from an epicormic bud, which lies underneath the bark of a trunk, stem, or branch of a plant.
Epicormic shoots sprouting vigorously from epicormic buds beneath the bushfire damaged bark on the trunk of a Eucalyptus tree
Epicormic buds lie dormant beneath the bark, their growth suppressed by hormones from active shoots higher up the plant. Under certain conditions, they grow into active shoots, such as when damage occurs to higher parts of the plant, or light levels are increased following removal of nearby plants. Epicormic buds and shoots occur in many woody species, but are absent from many others, such as most conifers.