Virginia Tech Dendrology

European black alder Betulaceae Alnus glutinosa (L.) Gaertn. symbol: ALGL2
Leaf: Alternate, simple, oval to orbicular, 2 to 4 inches long, 2 to 3 inches wide, rounded or slightly notched tip, doubly serrate margin, dark green above, lighter below with some scruffy pubescence in vein axils.
Flower: Species is monoecious; males slender, reddish-brown catkins (1 to 1 1/2 inch long), much longer when shedding pollen; females small (1/6 inch) reddish-brown, cone-like catkins in clusters near branch tips.
Fruit: Cone-like woody catkin, initially green, turning brown when ripe, 3/4 inch long, egg-shaped, contain many small winged nutlets, persistent through winter.
Twig: Green and sticky when young, later turning greenish brown; buds are stalked, purplish brown in color and somewhat three sided.
Bark: Initially smooth and grayish green, later turning grayish brown and developing irregular, small broken patches.
Form: Medium tree with a very narrow, upright crown; in its native habitat it reaches 80 feet tall and several feet in diameter; rarely get very large in North America.
Looks like: Italian alder - red alder - Arizona alder - hazel alder

Additional Range Information: Alnus glutinosa is planted in the USDA hardiness zones shown above and may seed into the landscape. Download the full-size PDF map.
More Information: Fall Color
External Links: USDAFS Silvics of North America - USDA Plants Database - Horticulture Information
All material 2021 Virginia Tech Dept. of Forest Resources and Environmental Conservation; Photos and text by: John Seiler, Edward Jensen, Alex Niemiera, and John Peterson; Silvics reprinted from Ag Handbook 654; range map source information