Term:

Understory tree
Definition:

A species of tree in which adult individuals do not reach the more-or-less continuous canopy tree layer of a forest.
Notes:

In the Lecythidaceae, a tree that is less than or equal to 20 m in height is considered to be an understory tree. The Lecythidaceae are predominately species found at elevations lower than 1000 meters and in vegetation without water restrictions but our definition of understory, canopy, and emergent does not consider these differences. In others words, our classification of understory, canopy, and emergent is applied to species as if it were growing in a standardized lowland forest.