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: 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.
	USDAFS Silvics of North America - USDA Plants Database Alnus glutinosa is planted in the highlighted USDA hardiness zones to the left and may seed into the landscape. See a map of the states in which European black alder has escaped (opens a new window).