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Picea

This article is about the tree. For other uses, see Spruce (disambiguation).
Spruce
Norway Spruce (Picea abies)
Scientific classification
Kingdom: Plantae
Division: Pinophyta
Class: Pinopsida
Order: Pinales
Family: Pinaceae
Subfamily: Piceoideae
Frankis
Genus: Picea
Mill.
Species

About 35; see text.

A spruce is a tree of the genus Picea /pˈsə/,[1] 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 metres (66–197 ft) 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).

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.[2]

Classification

DNA analyses[3][4] have shown that traditional classifications based on the morphology of needle and cone are artificial. A recent study[3] 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.

Species

There are thirty-five named species of spruce in the world.



Basal species:

Basal species

  • Clade I
  • Clade II
  • Clade III

Uses

Timber

Spruce is useful as a building wood, commonly referred to by several different names including North American timber, SPF (spruce, pine, fir) and whitewood. Spruce wood is used for many purposes, ranging from general construction work and crates to highly specialised uses in wooden aircraft, and as a tonewood in many musical instruments, including guitars, mandolins, cellos, violins, and the soundboard at the heart of a piano and the harp. The Wright brothers' first aircraft, the Flyer, was built of spruce.[5]

Because this species has no insect or decay resistance qualities after logging, it is generally recommended for construction purposes as indoor use only (ex. indoor drywall framing). Spruce wood, when left outside cannot be expected to last more than 12–18 months depending on the type of climate it is exposed to.

Pulpwood

Spruce is one of the most important woods for paper uses, as it has long wood fibres which bind together to make strong paper. The fibres are thin walled and collapse to thin bands upon drying. Spruces are commonly used in mechanical pulping as they are easily bleached. Together with northern pines, northern spruces are commonly used to make NBSK. Spruces are cultivated over vast areas as pulpwood.

Food and medicine


The fresh shoots of many spruces and pines are a natural source of vitamin C.[6] Captain Cook made alcoholic sugar-based spruce beer during his sea voyages in order to prevent scurvy in his crew.[7][8] The leaves and branches, or the essential oils, can be used to brew spruce beer.

The tips from the needles can be used to make spruce tip syrup . In survival situations spruce needles can be directly ingested or boiled into a tea.[9] This replaces large amounts of vitamin C. Also, water is stored in a spruce's needles, providing an alternative means of hydration . Spruce can be used as a preventive measure for scurvy in an environment where meat is the only prominent food source .

Other uses

The resin was used in the manufacture of pitch in the past (before the use of petrochemicals); the scientific name Picea is generally thought to be derived from Latin pix, pitch (though other etymologies have been suggested).

Native Americans in North America use the thin, pliable roots of some species for weaving baskets and for sewing together pieces of birch bark for canoes. See also Kiidk'yaas for an unusual golden Sitka Spruce sacred to the Haida people.

Spruces are also popular ornamental trees in horticulture, admired for their evergreen, symmetrical narrow-conic growth habit. For the same reason, some (particularly Picea abies and P. omorika) are also extensively used as Christmas trees.

Spruce branches are also used at Aintree racecourse, Liverpool, to build several of the fences on the Grand National course. It is also used to make sculptures and Christmas trees.

Etymology

The word "spruce" entered the English language from Old French Pruce, the name of Prussia. Spruce was a generic term for commodities brought to England by Hanseatic merchants and the tree was believed to have come from Prussia.[10] According to a different theory, some suggest that it may however be a direct loanword from a Polish expression [drzewo / drewno] z Prus which literally means "[tree / timber] from Prussia". That would suggest that the late mediaeval Polish-speaking merchants would import the timber to England and the English would pick up the expression from them.

References

External links

  • Arboretum de Villardebelle: Cones of selected species of Picea: Arboretum de Villardebelle page 2

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