More Alders identification

Here is information on three more types of Alder  – Italian Alder Alnus cordata, Grey Alder Alnus incana and Green Alder Alnus viridis – which you may come across in Britain. For details of the Common Alder click HERE

More Alders identification  – Italian, Grey and Green – tree shape, leaf shape, male and female catkins.

 

Italian Alder tree

The Italian Alder Alnus cordata, native to Italy and Corsica, was introduced in 1820 and is now common in parks, gardens and urban areas. It grows rapidly and is highly tolerant of urban pollution. It has catkins like the other Alders but the female cone-like catkins are bigger than those on the Common and Grey Alder. It has glossy heart-shaped leaves that stay on the tree until November.

Grey Alder tree

The Grey Alder Alnus incana is a medium sized tree that grows in poor soils and tolerates air pollution. It is native to the mountains of Europe and the Caucasus, except Britain, and was introduced in 1780. It is used on reclamation sites and in urban areas. Like all Alders it fixes nitrogen and improves the soil. It has catkins and can be confused with the Common Alder and Italian Alder but it has smaller cone-like catkins, a different leaf shape and smooth bark.

Green Alder shrub

The Green Alder Alnus viridis is a bush or small tree native to the mountains of central and south-eastern Europe. It was introduced to Britain in 1820 but it is rare and only found in a few collections. It grows well on poor soils. In the Alps its natural habitat is on steep, north-facing slopes at elevations of 1000 to 2000m but it is increasingly colonising abandoned sub-alpine pastures.

Italian Alder  leaf

 The Italian Alder leaf is heart shape with a pointed end, quite different from that of the Common Alder which has a blunt indented end.

Grey Alder leaf

The Grey Alder leaf is oval and pointed and has deeper teeth than other Alders.

Green Alder leaf

The upper side of the Green Alder leaf is dull green. The leaf has very fine, sharp teeth and 8 or 9 pairs of veins.

Italian Alder male catkins

Close-up of the Italian Alder male catkins in March before shedding pollen. The red anthers are not yet open to release pollen.

Grey Alder catkins

Grey Alder male catkins, hanging down, with a small female catkin, sticking up at the top. Photo in October. They will shed pollen in the following February.

Green Alder male catkins

Green Alder male catkins at the end of October.

Italian Alder  female cone

Woody, cone-like, female catkins of the Italian Alder are bigger than any other alder. This is a catkin that has released its seeds in autumn, photographed in the following July

Grey Alder female cones

Grey Alder female, cone-like, catkins in October. The one on the left is ready to shed seeds, those on the right have already shed seeds. The catkins are smaller than those of other Alders.

Green Alder female cones

The Green Alder female catkins are cone-like and similar in size to those of the Common Alder. Photo taken in August.