Trees, to 20 m; trunks often several, crowns narrow. Bark dark brown, smooth, becoming darker and breaking into shallow fissures in age; lenticels pale, horizontal. Winter buds stipitate, ellipsoid to obovoid, 6-10 mm, apex obtuse; stalks 2-5 mm; scales 2-3, outer 2 equal, valvate, usually heavily resin-coated. Leaf blade obovate to nearly orbiculate, 3-9 × 3-8 cm, leathery, base obtuse to broadly cuneate, margins flat, coarsely and often irregularly doubly serrate to nearly dentate, major teeth acute to obtuse or rounded, apex often retuse or obcordate, or occasionally rounded; surfaces abaxially glabrous to sparsely pubescent, often more heavily on veins, both surfaces heavily resin-coated. Inflorescences formed season before flowering and exposed during winter; staminate catkins in 1 or more clusters of 2-5, 4-13 cm; pistillate catkins in 1 or more clusters of 2-5. Infructescences ovoid to nearly globose, 1.2-2.5 × 1-1.5 cm; peduncles 1-10(-20) mm. Samaras obovate, wings reduced to narrow, thickened ridges.

Alterative, astringent, cathartic, febrifuge and tonic (bark); astringent, galactogogue and vermifuge (leaves)

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Alnus glutinosa
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