Tree also known as the trembling poplar (5)
I believe the answer is:
aspen
(Other definitions for aspen that I've seen before include "Tremulous poplar" , "Tree that quivers" , "Growth" , "Very timid" , "winter resort" .)
I believe the answer is:
aspen
(Other definitions for aspen that I've seen before include "Tremulous poplar" , "Tree that quivers" , "Growth" , "Very timid" , "winter resort" .)