Spruce refers to trees of the genus Picea, a genus of about 35 species of coniferous evergreen trees in the Family Pinaceae, found in the northern temperate and boreal (taiga) regions of the earth. Spruces are large trees, from 20–60 (–95) m 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 sterigmata. The needles are shed when 4–10 years old, leaving the branches rough with the retained sterigmata (an easy means of distinguishing them from other similar genera, where the branches are fairly smooth).
Spruces are used as food plants by the larvae of some Lepidoptera species; see list of Lepidoptera that feed on spruces. They are also used as food plants by Gall Adelgids (Adelges species).
The word "spruce" derives from an obsolete term for Prussia.
Scientists have found a cluster of Norway Spruce in the mountains in western Sweden which, at an age of 9,550 years, is the world's oldest known living trees.
