A spruce is a tree of the genus Picea /paɪˈsiːə/, 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 about 20–60 metres (about 60–200 feet) 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. The needles are shed when 4–10 years old, leaving the branches rough with the retained pegs (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 (moth and butterfly) species; see list of Lepidoptera that feed on spruces. They are also used by the larvae of gall adelgids (Adelges species).
In the mountains of western Sweden scientists have found a Norway spruce tree, nicknamed Old Tjikko, which by reproducing through layering has reached an age of 9,550 years and is claimed to be the world's oldest known living tree.[