The term “alder” is used to describe trees and shrubs in the genus Aldus, which is widely spread throughout the temperate zones of the Northern Hemisphere. There are a number of uses for alder wood, ranging from smoking fish to furniture, and it is an enduring and popular wood, especially in the United States.
Alders are deciduous, losing their leaves in the winter, and they are also flowering, bearing flowers in the form of catkins. Catkins are cylindrical clusters of very small flowers which look sort of like drooping, feathery fingers; pollen from the male catkins reaches the much smaller female catkins, which develop into cone-like structures once they are fertilized. The trees have simple, toothed leaves, and distinctively scaly bark which often grows deeply pitted in older specimens.
These trees are members of the birch family, Betulaceae, and they prefer moist, cool environments. You can often find alder trees along a stream, for example, and some people use the trees to identify potential sources of underground water and springs. Alders are also very sturdy, fast-growing trees, which can be a distinct advantage after a fire or on damaged land. In some regions, alders are planted for erosion control, to prevent the loss of topsoil in regions which have been denuded of vegetation. The trees also provide habitat for birds, and they often pair with nitrogen fixing bacteria, improving the soil where they grow.
One particularly famous variety of alder is the red alder, which produces distinctively colored wood. The wood is in fact red when freshly harvested, although it mellows to a rich yellow as it ages. Many furniture makers like to use red alder, and it is also well suited to smoking. The durability of the wood is also a valuable trait; alder wood is resistant to rot and insect infestations, which is why many people used it historically in foundations.
In addition to being used for their wood, alders can also be planted for ornamental purposes. Some people find alders quite aesthetically pleasing, and because they grow quickly, they can be planted in an area where a privacy screen is considered important. The trees take well to pruning and shaping, for people who want a more controlled look, or they can be allowed to grow naturally, in which case a thicket will gradually form.