Red Alder (Alnus rubra)

A. oregona.
Common Name Latin Name Plant Family
Red Alder
Alnus rubra

A fast-growing and very wind resistant tree, it is an excellent plant for providing rapidly produced shelterbelts[K]. The trees extensive root system also makes it suitable for controlling erosion along the banks of rivers[226].

This is an excellent pioneer species for re-establishing woodlands on disused farmland, difficult sites etc[226]. Its fast rate of growth means that it quickly provides sheltered conditions to allow more permanent woodland trees to become established. In addition, bacteria on the roots fix atmospheric nitrogen – whilst this enables the tree to grow well in quite poor soils it also makes some of this nitrogen available to other plants growing nearby. Alder trees also have a heavy leaf canopy and when the leaves fall in the autumn they help to build up the humus content of the soil. Alder seedlings do not compete well in shady woodland conditions and so this species gradually dies out as the other trees become established[K].

Tannin is obtained from the bark and the strobils[82].

Both the roots and the young shoots have been used in making baskets[257].

A red to brown dye is obtained from the bark[61, 118, 257].

Wood – soft, brittle, not strong, light, close and straight-grained, very durable in water[82]. An important lumber tree, it makes a good imitation mahogany[60, 103] and is used for cheap furniture etc[46, 61, 82, 171, 229]. A good fuel, it does not spark so can be used in the open[60, 118, 172], it also makes a high grade charcoal[103].

  • Medicinal Use

    Red alder was widely employed medicinally by native North American Indians who mainly used the bark to treat a wide range of complaints[257]. The plant is little used in modern herbalism[K].

    The bark is appetizer, astringent, cathartic, cytostatic, emetic, stomachic and tonic[61, 172, 257]. The bark contains salicin[226], which probably decomposes into salicylic acid (closely related to aspirin) in the human body[213]. This is used as an anodyne and febrifuge[226]. An infusion of the bark has been used in the treatment of many complaints such as headaches, rheumatic pains, internal injuries and diarrhoea[226, 257]. Externally, a poultice of the bark has been applied to eczema, sores and aches[257].

    The sap is applied externally to cuts[257].

    The catkins and young cones are astringent and have been chewed in the treatment of diarrhoea[257].

  • Edible Use

    Catkins – raw or cooked. They are rich in protein but have a bitter flavour and are not very palatable[172].

    Inner bark – cooked, It must be dried since it is emetic when fresh[105, 161, 177]. No more details are given but inner bark is often dried, ground into a powder and then used as a thickening in soups etc or mixed with cereals when making bread[K].

    Sap – raw[118]. Harvested in late winter, the flow is best on a warm, sunny day that follows a cold frosty night. A sweet flavour, it was often used to sweeten other foods[257].

    Buds[105, 177]. No further information is given, does this refer to the flower buds or leaf buds?[K]

  • Cautionary Notes

    The freshly harvested inner bark is emetic but is alright once it has been dried[172].

Cultivation & Habitat

Seed – best sown in a cold frame as soon as it is ripe and only just covered[200]. Spring sown seed should also germinate successfully so long as it is not covered[200, K]. The seed should germinate in the spring as the weather warms up. When large enough to handle, prick the seedlings out into individual pots. If growth is sufficient, it is possible to plant them out into their permanent positions in the summer, otherwise keep them in pots outdoors and plant them out in the spring. If you have sufficient quantity of seed, it can be sown thinly in an outdoor seed bed in the spring[78]. The seedlings can either be planted out into their permanent positions in the autumn/winter, or they can be allowed to grow on in the seed bed for a further season before planting them. Cuttings of mature wood, taken as soon as the leaves fall in autumn, outdoors in sandy soil.
Prefers a heavy soil and a damp situation[1, 11]. Grows well in heavy clay soils[11]. Tolerates very infertile sites[200]. A very wind resistant tree with excellent establishment in severely exposed sites, it tolerates severe maritime exposure[75, K]. The red alder is a very fast growing tree, even when planted in severe exposure[75, 229, K], but it is short-lived, dying when 60 – 80 years old[229]. Trees that are 5 years old from seed have reached 6 metres in height on a very exposed site in Cornwall, they are showing no signs of wind-shaping[K]. This is an important pioneer tree, quickly invading logged or burnt over sites, and providing ideal conditions for other trees to become established[229, K]. A very ornamental tree[1]. This species has a symbiotic relationship with certain soil micro-organisms, these form nodules on the roots of the plants and fix atmospheric nitrogen. Some of this nitrogen is utilized by the growing plant but some can also be used by other plants growing nearby[200]. Red alder has been estimated to fix as much as 300 kg of nitrogen per hectare[269].
Western N. America – Alaska to California.

Become ungovernable, break the chains of the matrix; grow and forage your own food and medicine.

*None of the information on this website qualifies as professional medical advice. Take only what resonates with your heart and use your own personal responsibility for what’s best for you. For more information [brackets] [000], see bibliography.