When does a tree become a tree?

Question:

When does a tree become a tree?

At what stage of development can one appropriate call a red maple tree (for the sake of argument)...a tree?

Best Answer - Chosen by Asker: Good question. This would appear (to me, at least) to be related to the Sorites Paradox, which doesn't really have a good answer. There's no clear dividing line between a seedling and a tree, as far as I can see.