Alnus glutinosa (L.) Gaertn. Common Alder or Black Alder
Native to Europe (including Britain), west Asia and north Africa. Grows wild in damp boggy ground and riversides, and its timber was used to make clogs in north England and Normandy. Little cultivated but sometimes planted as an ornamental in N. America. Height may reach 19m (65ft) or more. Male catkins shed pollen in early March, when they are 5-10cm (2-4in) long. Females are about 0.5cm (¼in) long. Fruit is 1-2cm (½-¾in). They turn woody through winter as shown with flowers. Leaves are rounded with an indented tip and 7 pairs of veins, each with long tufts of hair in axils underneath. Bark is dark brown, soon splitting into thick plates. Z6.
A. glutinosa cv. 'Imperialis' is one of the many cut-leaved forms, having deeply and narrowly lobed leaves. Grown in gardens where it never attains a large size.