subject: ALDER Anus glutinosa-a USEFUL TREE [print this page] The common Alder tree Alnus glutinosa belongs to the genus Alnus the Latin name for the alder tree. the common name is thought to derive from the Anglo-Saxon alor or aler. In Europe it is often known as the black alder, while in the U.K. it is simply the common alder. Various species of this tree occur in north America they include the Mountain Alder, Alnus tenuifolia White Alder,Alnus rhombifolia and the Red Alder,A.rubra.
In Scandinavian mythology the alder is said to be the tree from which woman was created. Conversely in Ireland the mythology conveys to us that the tree created man. The Alder tree came under attack from a fungal infection that destroyed many trees across Europe. It was first discovered in the U.K.,in the south of England during 1993. The fungi was thought to have been imported by way of introduced trees. The fungi belongs to the family Phytophthora which in days long ago caused the potato famine in Ireland. However, the reports of this disease seems to have diminished of late.
Alder has often been utilised as wind breaks. They are also employed by foresters to protect young more valuable timber saplings until they become established. Thus they are a good nurse crop.
The root of the alder tree contains nodules that are able to transfer nitrogen from the air into the ground which then become nutrient rich. The roots may sometimes be clearly seen in alder carrs in dry summer months when the water levels drop exposing the roots. The roots tend to have an orange colour making them almost unmistakeable. At first glance one can be forgiven for thinking that the roots are diseased, the bacteria is beneficial to the tree. Nitrogen helps the growth of stems, leaves, flowers and the seeds. Without nitrogen, growth of plants become stunted and the foliage may well turn a sickly yellow colour long before autumn occurs. There are other plants capable of transferring nitrogen from the air into the ground, these include very common plants such as nettle and clovers.
The bark is a smooth grey at first, becoming darker and more scaly with age. The twigs are hairless and of a grey brown colour. The tree thrives in wet ground for example by lakes, ponds and boggy ground in general. They can achieve the height of 20-30 metres but are generally smaller than this. They are thought to mature at around 60 years of age, and their life span is around 150 years. The young twigs, leaf buds and the young unfurling leaves are sticky caused by a resinous substance which nature has deemed to protect them from insect damage. This fact gives rise to the species name of glutinosa {glutinous-sticky}.
The short stalked rounded leaves 6-12cm long are toothed. The leaves become a dark glossy green colour as the summer progresses. Because they are a tree of wet soils the leaves remain green well into the autumn. The flowers of the alder are wind pollinated catkins. male and female grow on the same tree. The male catkins that appear in late winter and early spring are cylindrical but linear about 10cm long and of a reddish yellow colour. So many of these male catkins may adorn the tree , that from a distance, they can appear to be in full leaf. They hang down like tasselled ear rings from every twig. The female catkins are smaller being about 2cm long and are more tightly put together than the male catkins. reddish at first soon becoming green, and , during the summer months swell into the familiar barrel shaped cones. Indeed these cones make the alder an easy species to recognise for it is the only native British broad-leaved tree to produce cones all others that do so are coniferous such as pine or larch.
As the cones mature they become woody in nature and almost black in colour. The seeds contained inside the cones are much sought after by siskins and other finches during the winter months when seeds of other trees and plants are hard to locate. The seeds have a cork like outer layer that allow them to float in water, thus being carried away from their arboreal mothers to lodge in muddy banks where they will germinate.
The caterpillar of the alder moth is often associated with alder foliage, they are easily identified by their striking yellow and black segments. The Alder kitten moth may also be encountered, they too, are distinctive in their own way, being squat and angular with two whip-like tails.
The wood of the Alder is readily worked even when green. As the wood is worked it turns to a light orange colour which found favour with carpenters and furniture makers. The green wood was employed in the making of whistles and the beautiful sounding Pan Pipes in days gone by. It was employed in the country cottage industry providing wood for spinning wheels. Because of its affinity and great resistance to water the wood was utilised in the building of bridge supports and canal lock gates. It is not however, used in the construction of houses. The high protein level it contains attracts the larvae of a beetle. These larvae are commonly referred to as woodworm, indeed in days gone by, twigs of alder were placed in the drawers and chests of furniture made from more valuable wood such as oak to attract the wood worms to its protein, thus leaving the more valuable timber alone. These twigs were replaced at regular intervals. Alder was also employed in the tanning of leather.
Its medicinal uses have mainly become confined to the history books as far as home made medicinal remedies are concerned. It was considered to have a tonic and astringent properties. A decoction of the bark is useful to bathe swellings and inflammations, and was used as a gargle for sore throats. It has been stated that the heated leaves in a muslin bag is efficient at relieving the symptoms of rheumatism. Culpeper, the 17th century herbalist, recommended that the fresh leaves be placed under the feet of those galled by travelling. They were said to refresh and moisten the feet of people who had been walking all day.
