Latin name: Alnus
Number of species: about 30 alder species
circulation area: Europe, Asia, North America, South America
fruit: little nutlets
heyday: March April
height: 30 - 40 meters
Older: 80 - 120 years
Properties of the bark: ?
Properties of the wood: soft
Locations of the tree: moist soil
leaf: 5-10cm long, ovate, greenish color
Interesting about the alder
The genus of alder (Alnus) includes about 30 species worldwide, of which in Central Europe with Gray alder (White alder) Green alder (Alder alder) and the Alder three representatives emerge. Globally most of the alder species are found almost exclusively in the northern hemisphere in temperate climates.
A special feature of the alder is the symbiosis that they enter into with bacteria in order to be able to grow on nutrient-poor soils. For this, the so-called nodule bacteria in the roots bind molecular nitrogen and turn it into a condition that can be absorbed by the plant. In return, the alder provides the bacteria with a breeding ground where they can multiply, which is why one speaks of a symbiosis.
Among the preferred habitats are mainly permanently wet and swampy areas. This is also the reason why the alder stands have decreased significantly over the past fifty years. With increasing drainage of swamps, natural wetlands and smaller rivers, the alder habitat has also shrunk.