Tsuga

Tsuga chinensis var formosana

The hemlock or hemlock trees ( Tsuga ) are a genus of flowering plants in the family (Pinaceae ).

Designation

Hemlock is the translation of Engl. hemlock. The name comes from the smell of the crushed needles of the American West Hemlock, which strongly resembles the smell of Gierschs, a relatively close relatives of hemlock.

The scientific name Tsuga was introduced in 1847 by Stephan Ladislaus finite and is the Japanese name (Japanese栂) of the southern Japanese hemlock.

Description

Vegetative characteristics

The hemlock trees are evergreen trees with conical to irregular ovoid ( Asian in some species ) tree crown. The tops of the trees and the otherwise horizontal branches often hanging over. The bark is furrowed gray to brown, scaly and often deep. The oldest are probably Tsuga mertensiana, is told of them, there would be 1400 years old copies are detectable are 800 year old specimens in British Columbia. As the highest tree of the genus is a specimen of Tsuga heterophylla with a height of 55 meters, a trunk diameter ( dbh ) of 259 centimeters and a crown diameter of 20 meters at Quisitis Point in Pacific Rim National Park in British Columbia (report by Stolt man 1987). The more or less double spaced or around the branch needles arranged over last few years, are flat to slightly angular, with a base that is stalk -like and a pungent to rounded end. The stomata are located in two rows on needle bottom; only Tsuga mertensiana also stomata are on the top. Each needle has a resin channel. The buds are not resinous. The seedling has four to six cotyledons ( cotyledons ).

Generative features

Tsuga species are monoecious getrenntgeschlechtig ( monoecious ). Individually to one-year branches are the male cones, which are spherical, brown and smaller than 8 mm. The female cones are on one-year branches; they need five to seven months to ripen and fall soon after dismissing the seeds or remain on the tree for several years. The pin drops as a whole. The maximum hanging on very short stalks female cones are ovoid to oblong, only Tsuga mertensiana oblong- cylindrical. The cone scales are thin, leathery and variable in shape; they are usually smooth and hairy only on Tsuga mertensiana. The bracts are small.

The seeds have a length of 3 to 5 mm and a diameter of 2 to 3 mm. They have many small resin container. Your thin wings are 5-10 mm long.

The chromosome number is 2n = 12

Occurrence

Your areas ranging from the temperate zones of North America to East Asia. Tsuga - natural locations are always in relatively humid climates, with little drought stress. In their habitats they are often the dominant plants.

The genus Tsuga was in the Tertiary in Europe at home, but died out during the Ice Age.

System

The genus of hemlock ( Tsuga ) is divided into two sub- genera with eight species:

• Subgenus Tsuga: With seven types: Eastern Hemlock ( Tsuga canadensis Carriere )
• Carolina Hemlock ( Tsuga caroliniana Engelmann )
• Chinese hemlock ( Tsuga chinensis ( Franchet ) Pritzel ex Diels )
• Called Northern Japanese hemlock, or hemlock Unlike aristocrats, ( Tsuga diversifolia ( Maxim. ) Masters)
• Himalayan Hemlock ( Tsuga dumosa ( D.Don ) Eichler )
• Südjapanische Hemlock ( Tsuga sieboldii Carrière )

• Mountain hemlock ( Tsuga mertensiana ( Bongard ) Carriere )

Use

Few species are grown in forestry in Europe; Some species are planted partly as cultural forms, in parks and gardens. Due to its insensitivity to moisture hemlock is used in traditional archery as arrow shaft material. The moisture resistance in combination with the resin poverty of the wood make Hemlock a high quality material for sauna construction.

Pictures

Branch of the Carolina Hemlock ( Tsuga caroliniana ).

Branch with needles and cones of the southern Japanese hemlock ( Tsuga sieboldii )

Branch with needles of Northern Japanese Hemlock ( Tsuga diversifolia ).

Branch with needles of mountain hemlock ( Tsuga mertensiana ).

Swell

• Christopher J. Earle, 2009: Information on the genus at The Gymnosperm Database. (Section Description and systematics)