Thuja

Branch with scale-like leaves and ripe cones of Western life tree ( Thuja occidentalis).

Living trees or arborvitae (Thuja ) are a genus of flowering plants in the family of the cypress family ( Cupressaceae ) in the order of the pine -like ( Pinales ). There are two species in North America and three in eastern Asia.

The species and their varieties, except the Sichuan arborvitae (Thuja sutchuenensis ), are common in culture, but above all of Western arborvitae (Thuja occidentalis) is often used as a hedge plant.

Description

Thuja species and their varieties grow as evergreen trees or shrubs. The highest 53 -meter tree of the genus is the " Quinault Lake Cedar " north of Quinault Lake in the Olympic Mountains in Washington State. The strain with a trunk diameter of 594 cm is hollow, however, the tree a total volume of 500 m³. The scale-like leaves are arranged in four rows on the branches. They differ in surface and edge leaves and occasionally have oil glands.

Thuja species are monoecious getrenntgeschlechtig ( monoecious ), so there are male and female cones on a plant. The male cones have (four to ) six to ten (up to sixteen) Mikrosporophylle. Each microsporophyll has two to four pollen sacs. The female cones are individually terminally on the branches. You have four to six pairs of seed scales, of which only the middle, larger two to three pairs are fertile. The small, egg-shaped, leathery cones mature and open in the same year of pollination. Each fertile seed scale has one to three seeds. The seeds have two lateral, narrow wings.

The seedlings have two seed leaves ( cotyledons ).

Systematics and naming

The name " Tree of Life" is to be regarded as a pure book name in German because of its other meanings very misleading and in its use for the name of the genus. In German, the term " Thuja " is far more common.

In the life of the species trees (Thuja ), there are five types:

• Korean arborvitae (Thuja koraiensis Nakai, Syn: Thuja odorata )
• Western arborvitae (Thuja occidentalis L.)
• Giant Arborvitae (Thuja plicata Donn ex D. Don, Syn: Thuja gigantea Nutt. )
• Japanese arborvitae (Thuja standishii ( Gordon) Carriére )
• Sichuan arborvitae (Thuja sutchuenensis Franch. )

Another way of Oriental arborvitae or " Chinese Thuja " which was formerly known as Thuja orientalis assigned here, is now placed in a separate genus Platycladus orientalis Platycladus under the name.

The individual species of the genus Thuja include distinguishable on the aromatic scent of crushed flake-like leaves. So Thuja koraiensis smells of almond cake, Thuja plicata ( even without grinding ) of pineapple, Thuja occidentalis by applesauce with cloves and the smell of Thuja standishii reminiscent of lemon candy.

Fossil evidence

The infrequent fossil representatives (or close relatives ) of the genus Thuja are usually referred to as " Thuites ". Thuites branch remains are known from Jurassic deposits. At the tertiary members of this genus were undoubtedly also native to Europe. From the Eocene Baltic amber Thuites four species are described. Also from the deposit of the Bitterfeld amber, which is dated by some authors to a Miocene age, is equated by others with Baltic amber inclusions are preserved parts of plants of this genus.

Use

Wood

Trees of Life have a light, reddish-brown heartwood. It is very durable and valuable. The North American species are used in forestry and traded under the name " Red Cedar " (Thuja plicata) and " White Cedar " (Thuja occidentalis). The ingredients of the tree of life wood can cause allergies. Since the postwar period, wood shingles are red and later imported from a Canadian also of white cedar to Germany, which have better weather resistance than the native larch.

Naturopathy, toxicity

In naturopathy Thuja is used for the treatment of warts. The solution is applied to a cosmetic pad, and this set to the wart.

In particular branch tips, wood and cones are highly toxic by a contained essential oil and can cause skin irritation, so wear gloves when cutting the plant is useful in sensitive individuals. Ingested in sufficient quantities can be fatal poison.

Ornamental plant

The popularity of the trees of life as an ornamental plant is based on the excellent interface compatibility. After installation of a hedge is to start early with a section, the hedge should be based on a trapezoidal in cross section. Height can be a hedge in the older state are also greatly reduced. The width of this is very limited, because the tree of life verkahlt inside and not grow back from woody twigs and branches.