Professor Actual Factual and Brother Bear in “Unfinished Business”

That's another environment problem in Bear Country. [sees a piece of wood from a bumbleberry tree] And so is this. A sample to add to my endangered and extinct species display. [picks up the piece of wood from a bumbleberry tree]

But I thought endangered species were just animals, Professor.

Well, animals, plants, and even trees can become extinct or endangered.