Alder
(Alnus glutinosa)
Simple
Roundish
Alternate
Toothed
Broadest at tip

leaf

Winter twig
Winter twig

male and female catkins
(Male & female catkins)

cones and leaves showing blisters
(Cones and leaves showing blisters)

distribution map

The leaves are oval, 3-9 cm long and broadest towards the tip. They are borne alternately on the twigs. They are almost hairless, with fine teeth along the margins and are slightly sticky when young. The upper side is dark green but the lower side is paler. The leaf stalk is 1-3 cm long. The leaves often have small blisters on the upper surface caused by tiny mites (see photo).

ID check

Alder is a deciduous tree up to 15m or so often branching above the base. It grows where the water-table is high and is frequent along streamsides and in marshland.

The tree should have numerous small black, woody cones approximately 2 cm long which persist for several years. These started as female catkins each scale of which held two dark brown seeds.

The male catkins open on the same trees in spring, before the leaves, but soon fall.

The bark is rough and often sprouts young shoots.

Facts

  • The seeds are edged with air-filled tissue which enables them to float on water for about a month

  • The wood is easy to work with and has been used to make clogs, toys and cheap pencils

  • Alder charcoal was used to manufacture gunpowder as late as 1946.

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