Alnus rubra

Constantly changing arranged on the branches leaves of red alder.

The home in western North America red alder or Oregon alder ( Alnus rubra) is the world's largest flowering plant in the genus of alder ( Alnus ) from the birch family ( Betulaceae ). It grows in a 200 km wide strip along the Pacific coast, which extends from southeastern Alaska to California. At the height of the U.S. state of Washington, it is also another 600 km inland to be found in Idaho.

Description

The red alder is reached, a deciduous tree, the plant height of 20 to 35 m. The 32 m high tree stands currently in Clatsop County, Oregon (USA). Your name derives from the bright rusty - red color of its timber when it was freshly made. The bark is gray, smooth, and covered with small round Korkwarzen.

The change-constant leaves are ovate, 7-15 cm long, have rough sawn edges and are distinctly pointed. They are bent downwards. In this feature, they differ from the leaves of all other alder species. The leaves of red alder turning yellow in autumn before falling.

The red alder blooms in February and March, well before the leaves appear. It is monoecious getrenntgeschlechtig ( monoecious ). The male inflorescences are 10 to 15cm long, hanging down, reddish kitten. The female catkins are erect, growing to 2 to 3 cm long, woody cones. Pollination is about the wind. The seeds are also released by the wind in autumn and winter.

Dissemination

The red alder grows in southern Alaska, western British Columbia and the northwestern coastal mountains of the United States on cool, moist slopes. Here it is ( menziesii subsp Pseudotsuga. Menziesii) along with the Douglas fir, the western American hemlock ( Tsuga heterophylla ), the Grand Fir (Abies grandis), the giant arborvitae (Thuja plicata) and Sitka spruce (Picea sitchensis) forming stands.

Further inland and along the southern limit of distribution in California, it grows mainly along rivers and in swamp forests. Here it is often combined with willow, the Silky Dogwood (Cornus stolonifera ), Oregon ash (Fraxinus latifolia ) and the Oregon maple ( Acer macrophyllum ) found.

South-east of its range grows the white alder ( Alnus rhombifolia ). It is closely related to the red alder, but does not by curved sheets. In the high mountains grows instead of red alder, the smaller green alder ( Alnus viridis subsp. Sinuata ), east of the Cascade Range, the gray alder ( Alnus incana subsp. Tenuifolia ) is growing.

The red alder is a typical pioneer tree. It settles quickly by fire or clear-cutting resulting open spaces and prepared by their soil improvement before the growth of the above-mentioned conifers.

The red alder produces extremely many seeds that can germinate but only in the open mineral soil. In clear-cuts several hundred thousand or even several million seedlings per hectare may occur ( Zavitkovski & Stevens 1972) in the first year.

The red alder is to be bound by the bacterium Frankia alni capable of nitrogen from the air. This allows her to grow on nitrogen-poor soils.

Cultivation and uses

A red-yellow dye can be obtained by boiling the bark. It was used by the indigenous people of North and South America to dye fishing nets so that they were less visible in the water.

The red alder is an important tree for forestry. Their rapid growth makes them particularly suitable to colonize wastelands. Your numerous seeds are helping to enrich the humus with nitrogen when decomposed. It is alternately grown conifers to prevent the spread of the fungus Phellinus weirii, in particular the Douglas -fir attacks and severely damages.

The timber industry looked at earlier, the red alder as " weeds " and sprayed herbicides over large red alder forests in Oregon and Washington. The increasing value of the wood, coupled with a better understanding of the positive effects that has the red alder for other trees caused largely the setting of this practice.

The wood is not durable for outdoor use. However, it is used for furniture and other carpentry work. Previously, its value was considered to be very low, but now it was in the western U.S. to a fairly important hardwood. It's white, pink or light brown, can be easily processed, can be stick well and is durable.

Red alder trees are generally not planted as ornamental trees.