You have to click on the trees and they will tell you what spell to cast. I.e. if it says there's a picture of a panther, cast cat's grace. If there's a picture of half flesh, half tree, cast barkskin, etc.
A moment's thought should make it obvious. One has a picture of a cat on it, one a bear, one a bull, and one has a guy with -bark for skin-.
Open up Elenee's spellbook and look over her second level spells.