Spruce

A spruce is a tree of the genus Picea Sunset Western Garden Book, 1995:606–607 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 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. The needles are shed when 4–10 years old, leaving the branches rough with the retained pulvinus (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 by the larvae of Gall Adelgids (Adelges species).
Scientists have found Norway Spruce in the mountains in western Sweden, nicknamed Old Tjikko, which at an age of 9,550 years are claimed to be the world's oldest known living trees.Swedish Spruce Is World's Oldest Tree: Scientific American Podcast
==Classification==
DNA analysesRan, J.-H., Wei, X.-X. & Wang, X.-Q. 2006. Molecular phylogeny and biogeography of Picea (Pinaceae): Implications for phylogeographical studies using cytoplasmic haplotypes. Mol Phylogenet Evol. 41(2): 405–19.Sigurgeirsson, A. & Szmidt, A.E. 1993. Phylogenetic and biogeographic implications of chloroplast DNA variation in Picea. Nordic Journal of Botany 13(3): 233–246. have shown that traditional classifications based on the morphology of needle and cone are artificial. A recent study found that P. breweriana had a basal position, followed by P. sitchensis, and the other species were further divided into three clades, suggesting that Picea originated in North America.
There are thirty-five named species of spruce in the world.<[<BOTANY>]>SCIENCES Spruce
===Clade I===
:* Picea breweriana Brewer's Spruce. Klamath Mountains, North America; local endemic.
===Clade II===
:* Picea sitchensis Sitka Spruce. Pacific Coast of North America; the largest species, to 95m tall; important in forestry.
===Clade III===
:* Picea engelmannii Engelmann Spruce. Western North American mountains; important in forestry.
:* Picea glauca White Spruce. Northern North America; important in forestry.
===Clade IV===
:* Picea brachytyla Sargent's Spruce. Southwest China.
:* Picea chihuahuana Chihuahua Spruce. Northwest Mexico (rare).
:* Picea farreri Burmese Spruce. Northeast Burma, southwest China (mountains).
:* Picea likiangensis Likiang Spruce. Southwest China.
:* Picea martinezii Martinez Spruce. Northeast Mexico (very rare, endangered).
:* Picea maximowiczii Maximowicz Spruce. Japan (rare, mountains).
:* Picea morrisonicola Yushan Spruce . Taiwan (high mountains).
:* Picea neoveitchii Veitch's Spruce. Northwest China (rare, endangered).
:* Picea orientalis Caucasian Spruce or Oriental Spruce . Caucasus, northeast Turkey.
:* Picea purpurea Purple Spruce. Western China.
:* Picea schrenkiana Schrenk's Spruce. Mountains of central Asia.
:* Picea smithiana Morinda Spruce. Western Himalaya.
:* Picea spinulosa Sikkim Spruce. Eastern Himalaya.
:* Picea torano Tiger-tail Spruce. Japan.
:* Picea wilsonii Wilson's Spruce . Western China.
===Clade V===
:* Picea abies Norway Spruce. Europe; important in forestry. The original Christmas tree.
:* Picea alcoquiana ("P. bicolor") Alcock's Spruce. Central Japan (mountains).
:* Picea alpestris Norway Spruce, Alpine Spruce. The Alps in Europe; rare, often treated as a variant of P. abies (and hybridises with it) distinct cones.
:* Picea asperata Dragon Spruce. Western China; several varieties.
:* Picea crassifolia. China.
:* Picea glehnii Glehn's Spruce. Northern Japan, Sakhalin.
:* Picea jezoensis Jezo Spruce. Northeast Asia, Kamchatka south to Japan.
:* Picea koraiensis Korean Spruce. Korea, northeast China.
:* Picea koyamae Koyama's Spruce. Japan (mountains).
:* Picea mariana Black Spruce. Northern North America.
:* Picea meyeri Meyer's Spruce. Northern China (from Inner Mongolia to Gansu).
:* Picea obovata Siberian Spruce. North Scandinavia, Siberia. Often treated as a variant of P. abies (and hybridises with it) but distinct cones.
:* Picea omorika Serbian Spruce. Serbia; local endemic; important in horticulture.
:* Picea pungens Blue Spruce or Colorado Spruce. Rocky Mountains, North America; important in horticulture.
:* Picea retroflexa. China.
:* Picea rubens Red Spruce. Northeastern North America; important in forestry. Known as Adirondack in musical instrument making.
==References==