Alnus incana, the grey alder or speckled alder, is a species of multi-stemmed, shrubby tree in the birch family, with a wide range across the cooler parts of the Northern Hemisphere. Tolerant of wetter soils, it can slowly spread with runners and is a common sight in swamps and wetlands. It is easily distinguished by its small cones, speckled bark and broad leaves. Description It is a small- to medium-sized tree tall with smooth grey bark even in old age, its life span being a maximum of 60 to 100 years. The leaves are matte green, ovoid, long and broad. The flowers are catkins, appearing early in spring before the leaves emerge, the male catkins pendulous and long, the female catkins long and one cm broad when mature in late autumn. The seeds are small, long, and light brown with a narrow encircling wing. The grey alder has a shallow root system, and is marked not only by vigorous production of stump suckers, but also by root suckers, especially in the northern parts of its range. The wood resembles that of the black alder (Alnus glutinosa), but is somewhat paler and of little economic value. Subspecies There are four to six subspecies, some treated as separate species by some authors: Alnus incana subsp. incana; grey alder — Northern Europe and northwestern Asia, and central and southern Europe in mountains, mainly in the regions of the Alps, Carpathians and the Caucasus Alnus incana subsp. hirsuta (=A. hirsuta ); Manchurian alder — In mountains of Northeast Asia and Central Asia Alnus incana subsp. kolaensis — Subarctic northeast Europe Alnus incana subsp. oblongifolia (=Alnus oblongifolia); Arizona alder — Madrean Sky Islands of southwestern North America, in Arizona, New Mexico, and Northwestern Mexico Alnus incana subsp. rugosa (=A. rugosa ); speckled alder — Much of Canada below the tree line, and the Northeastern United States Alnus incana subsp. tenuifolia (=A. tenuifolia ); mountain alder, or thinleaf alder — Western North America, including New Mexico to California and Alaska; the roots have nitrogen-fixing nodules. Ecology Alnus incana is a light-demanding, fast-growing tree that grows well on poorer soils. In central Europe, it is a colonist of alluvial land alongside mountain brooks and streams, occurring at elevations up to . However, it does not require moist soil, and will also colonize screes and shallow stony slopes. In the northern part of its range, it is a