Wow, I google it and didn't found anything too, I thought that it was a common term accepted by games and mythology of living trees that can move out of the ground and speak. At least Wose is the name of those trees on Wesnoth.

Here is a new list of units:

Consider that the plague effect takes place at the end of the opponent turn (so the enemy can kill this unit or other before transforming).

If the enemy has 0 value, the trigger doesn't activate (you don't lose 1 morale each turn for being adjacent to a creature with 0 value).
If the enemy has 2 or 1 value, you only gain 2 or 1 value (respectively).