Alnus glutinosa.
Common name Alder and other species
Alnus or 'Alders' are a group of trees native to Europe and areas of Asia. Alnus glutinosa is the 'Black' or 'Common Alder'. Alnus incana and alnus cordata are other species to consider. The Alder is a hardy, deciduous, tree or shrub. There are 35 different species of Alder, many available for sale in the UK.
Growing conditions and Care
The Common or Black Alder: Alnus glutinosa is native to the UK. This Alder can be planted in inhospitable areas such as those that remain wet all year. A. glutinosa has a fast growth rate when young then slows to a moderate rate. The tree grows to around 25m with a spread of 10m. It can be grown as a single trunk specimen tree in the garden if pruned in winter into a single trunk. It can also be left in multi trunk form and makes an excellent country-style hedge or screening plant for privacy in your garden.
The Common or Black Alders are a great solution in a garden area that has wet or infertile soil. The tree actually improves soil fertility by its ability to fix nitrogen. The root nodules contain bacteria that produce water soluble nitrogen compounds. The younger tree has smooth grey bark that becomes rougher and dark brown with age. The Alder is broadleaved. The leaves are dark green, serrated and alternate on the stem. They take on a purple sheen in spring. The flowers are called catkins and will attract bees and butterflies to your garden.
The Common Alder catkins appear on the tree before the leaves. The male catkins are 2-4 inches long and a yellow/brown colour. The Alder fruit, which develop from the female catkins, are small oval and cone shaped. They grow in clusters after the flowers have finished. The root system is a combination of tap root and wide spreading shallow roots.
This combination makes the Alder able to withstand high winds and the roots quickly bind loose or rocky earth. Due to the fibrous and strong characteristics of the roots it is recommended to avoid planting Alders close to drains and water pipes. Alder wood is fine grained with a beautiful colour. It does not split easily so is excellent for carving and turning.
The Alder can be propagated from layering, cuttings and more usually by seeds which are planted from October to April.
Alnus species and cultivars.
- Italian Alder (Alnus cordata) has a mature height of 10 m. Suitable as a specimen tree; it is very hardy and has a pyramidal shape. Leaves have an attractive texture and the male catkins are ornamental.
- The Red Alder (Alnus rubra) This is a deciduous tree native to Western North America. It can be used by gardeners as an ornamental tree. It enjoys a cool cli
mate where there is high humidity. It is commonly propagated by coppicing and by layering. The wood is beautiful and is often used for furniture.
- Grey Alder (Alnus incana) is a small to medium sized tree that multiple curved trunks.
- Golden Alder (Alnus incana aurea) is a beautiful warm yellow alder with deep pink catkins has the same characteristics of the Grey Alder.
You may also be interested in
Alder or Alnus species are available for sale from the following nurseries
CHEW VALLEY TREES
Winford Road Chew Magna Bristol BS40 8HJ - Tel: 01275 333 752
Tree nursery selling top quality specimen and ornamental bare root and container grown trees, shrubs, hedging and fruit trees. Available wholesale and retail nationwide. INCLUDES: ALNUS GLUTINOSA
