|Alnus glutinosa is a deciduous alder tree, 40 to 60 feet in height, 20 to 40 feet in spread; can reach 100 feet tall. Small trees are often multi-stemmed and pyramidal, can also develop an oblong or rounded irregular crown. Bark is a lustrous gray-green in young trees, older specimens have a polished brown coloration. Foliage is dark glossy green, can develop yellow fall color, more often leaves fall off green. Male flower is a reddish catkin, female is a purplish strobile, not conspicuous.
Fruit is a winged nutlet, fall maturing. Prefers moist to wet soil , but adaptable to dry, it will seed itself if planted along stream banks. Nitrogen fixing species, does not require fertilization usually, not tolerant of heat. Subject to some pests, but not usually serious. Good choice for difficult, wet sites, infertile areas. Native to Europe, western Asia and Africa, naturalized in areas of the U.S. Several cultivars are available.