If you are trying to describe a small tree, these are words you can use.
For the seed; more often the seed which has fallen off. Use ``pod``.
For a small but growing tree ``sprout``.
The amount of leaves a tree has. For less ``This tree has very little foliage``, for more ``this tree has plenty of foliage
Note that I am not using scientific words for plants, and that there are many words to describe trees and plant life.