He looks thoughtful for a moment, "Tree nymphs and forest spirits." He runs a hand through his hair, as if that would help his completely muddled thought process. "Teraforming in colonies and such, but those are more bacteria related." He shrugs.

"BUT you," The Doctor prods Ned in the arm, "Don't quite resemble one, so I'm noooooot sure what has made you cause this."

He looks over, and plucks a petal from a flower and sticks it in his mouth, making a face, "Oh... Not Time Lord! Bleh. Is that how you humans really taste things?"