Trees Planet: Picea sitchensis

Wednesday, May 31, 2017

Picea sitchensis – Sitka Spruce

General Information

Common Name	Sitka Spruce
Scientific Name	*Picea sitchensis*
Sun Tolerance	Full Sun
Height	upto 100 m (upto 330 ft)
Spread	15 - 30 m (50 - 100 ft)
Growth Rate	Fast
Bloom Time	Spring
Color	Green,
Flower Color	Yellow
Type	Tree
Native	USA, Asia, Europe.

Classification

Kingdom	Plantae – Plants
Subkingdom	Tracheobionta – Vascular plants
Superdivision	Spermatophyta – Seed plants
Division	Coniferophyta – Conifers
Class	Pinopsida
Subclass
Order	Pinales
Family	Pinaceae – Pine family
Genus	Picea – Spruce
Species	P. sitchensis

Picea sitchensis – Sitka Spruce

Picea sitchensis commonly known as Sitka spruce. Its introduced by David Douglas in 1831 is nowadays the most extensively planted tree in British forestry. It takes its name from the small seaport of Sitka in Alaska, but is found as a native southwards from that state to north California. It is a large growing tree, grow up to 100 m (330 ft), with huge trunk up to 5m (16 ft) in diameter.

The young shoots are light brown to pure white. The buds are ovoid and yellowish-brown and free of resin. The needles stand out stiffly around the shoot, and are bluish-green on the upper surface, with a prominent rib; the lower surface bears two bands of white stomata giving a blue or silvery appearance. The needles are flattened up to 2 cm long and have sharp horny points. Each needle stands on a little peg projecting from the twig; when pulled away, the peg goes with the needle, accompanied by a short strip of bark. In mass the needles give the tree a faintly blue sheen.

The flowers of both sexes are found on the same tree. The stalked male catkins are about 2.5 cm long, oval, pendulous or spreading, red at first but becoming yellow. The female flowers, usually higher up the tree, are small oval, erect structures, stalk less and crimson-colored; they have prominent bract which are eventually covered by the developing scales. The cone, 5-8 cm long and blunt-ended, has papery-textured scales with crinkled edges, and is light brown becoming whitish or pale yellow. It ripens in the first year, releasing the seeds early in autumn and then persisting on the tree for indefinite periods.

The bark is at first greyish-brown and looks smooth (though rough to the touch), later breaking into greyish-brown round scales, with somewhat raised edges (in appearance like small shallow saucers), which gradually flake away. The tree is at first conical in shape, later developing long lightly drooping branches and a rather thin crown. The base usually broadens out and is often buttressed. The wood is tough but has no natural durability out of doors; it is white to pale yellow in color – much used for box-making, interior joinery and carpentry, shed-building, paper pulp, chipboard, pit-props, and general purposes.

Foresters appreciate Sitka Spruce as a fine forest tree for the peaty hills and moors where the rainfall is heavy. It is more resistant to exposure and possibly more wind-firm than Norway Spruce and in general faster growing and produces a larger volume of timber. It can exceed 100 feet in thirty years and several trees are known over 150 feet and some exceed 20 feet in girth. Sitka particularly in drier areas is partially defoliated annually by the attacks of an aphis Elatobium abietina, making the tree appear much thinner foliaged than Norway Spruce. High moisture requirements make it unsuitable for the drier climates and soils of the south and east of Britain.

This is also use as Christmas Trees.