Who gets turned into a tree in “Tortall and Other Lands”?

Question

In the book Tortall and Other Lands, there is a story about a tree who becomes a man because Numair turns a man into an apple tree, and there has to be balance.

Do any of Tamora Pierce's other books mention who Numair turns into a tree? It seems like a pretty major thing.

Answer 1

The mage's name was Tristan Staghorn (in Pierce's novel Wolf-Speaker).