Spruces are large trees , from 20 â `` 60 ( â `` 95 ) m tall when mature , and can be distinguished by their conical form and their needles , that are attached singly to the branches in a spiral fashion . Spruces are large trees , from 20 â tall when mature , and can be distinguished by their whorled branches and conical form . The needles , or leaves , of spruce trees are attached singly to the branches in a spiral fashion , each needle on a small peg-like structure called a pulvinus .