Black Alder (Alnus glutinosa)

/ / Trees and Shrubs


Alnus is a genus that contains mostly deciduous trees that have alternate simple toothed leaves and flowers that form into catkins.  They are mainly found in northern temperate regions (1)Alnus glutinosa is a medium sized tree reaching height of 20 m in Greece (2), however in ideal conditions it can reach to 35 m (3).  It has a straight trunk with spreading branches.  Its leaves are bright green, glandular and obovate to elliptical in shape.  Male flowers group together in catkins whilst the female flowers are green and egg shaped and also form catkins (2).

Life Cycle

It is a deciduous tree which forms vertical fissures in its bark at maturity.  The flowers at maturity form into what looks like small woody cones containing the seeds (2).


It likes wet places on the banks of rivers, streams and ravines (2).  It is also capable of growing in marshes with its roots completely submerged (3).  It grows in montane and semi-montane areas (2).


It can be found across Europe and northern and central Greece (2).

Conservation status

IUCN Red List = Least concern (4).

It falls under the Habitats Directive Annex I as ‘Alluvial forests with Alnus glutinosa and Fraxinus excelsior(5)


Description written by Amy Trayler (2009)

(1)   Answers (2007) Alder [online] Available: [date accessed: 08/05/2009]

(2)   Sfikas. G. (2001) Trees and Shrubs of Greece, Efstathiadis Group S.A., Greece

(3)   Royal Botanic Gardens, Kew (2009) Alder Alnus glutinosa [online] Available: [date accessed: 08/05/2009]

(4)   IUCN 2008 (2008) IUCN Red List of Threatened Species [online] Available: [date accessed: 07/05/2009]

(5)   Joint Nature Conservation Committee (2009) UK Interest Features [online] Available: [date accessed: 19/06/2009]