Red Alder, Oregon Alder
Alnus rubra

Family: Betulaceae

What it is like

Main Bloom Time: Early spring, Late spring, Mid spring. Form: Oval, Pyramidal.

Alnus rubra is a deciduous Tree growing to 20 m (65ft 7in) at a fast rate. See above for USDA hardiness. It is hardy to UK zone 6. It is in flower in March, and the seeds ripen from September to October. The species is monoecious (individual flowers are either male or female, but both sexes can be found on the same plant) and is pollinated by Wind. It can fix Nitrogen. Suitable for: medium (loamy) and heavy (clay) soils and can grow in heavy clay and nutritionally poor soils. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It can grow in semi-shade (light woodland) or no shade. It prefers moist or wet soil. The plant can tolerate maritime exposure.

Height (m): 20

Where it is found

Moist rich soils in woods, usually below 600 metres and within 50 km of the coast.

Western N. America - Alaska to California.

Conservation Status:

Countries/locations it is found in

How it is used

Food

Rating: 2

Catkins - raw or cooked. They are rich in protein but have a bitter flavour and are not very palatable. Inner bark - cooked, It must be dried since it is emetic when fresh. 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. Sap - raw. 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. Buds. No further information is given, does this refer to the flower buds or leaf buds?

Inner bark: the bark that is found just beneath the tough outer bark of trees and shrubs.

Sap: usually of trees and usually but not always used as a drink.

Medicine

Rating: 2

Red alder was widely employed medicinally by native North American Indians who mainly used the bark to treat a wide range of complaints. The plant is little used in modern herbalism. The bark is appetizer, astringent, cathartic, cytostatic, emetic, stomachic and tonic. The bark contains salicin, which probably decomposes into salicylic acid (closely related to aspirin) in the human body. This is used as an anodyne and febrifuge. An infusion of the bark has been used in the treatment of many complaints such as headaches, rheumatic pains, internal injuries and diarrhoea. Externally, a poultice of the bark has been applied to eczema, sores and aches. The sap is applied externally to cuts. The catkins and young cones are astringent and have been chewed in the treatment of diarrhoea.

Anodyne: Relieves pain, it is milder than an analgesic.

Appetizer: Improves the appetite

Astringent: Produces contraction in living tissue, reducing the flow of secretions and discharges of blood, mucus, diarrhoea etc.

Cathartic: A strong laxative but less violent than a purgative.

Cytostatic: Slows or controls the growth of tumours.

Eczema: Used in the treatment of eczema - a chronic health condition that affects the skin, causing redness, dryness, itching and infections.

Febrifuge: Reduces fevers.

Skin: Plants used in miscellaneous treatments for the skin.

Stomachic: Aids and improves the action of the stomach.

TB: Plants used in the treatment of tuberculosis

Tonic: Improves general health. Slower acting than a stimulant, it brings steady improvement.

Other

Rating: 4

A fast-growing and very wind resistant tree, it is an excellent plant for providing rapidly produced shelterbelts. The trees extensive root system also makes it suitable for controlling erosion along the banks of rivers. This is an excellent pioneer species for re-establishing woodlands on disused farmland, difficult sites etc. 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. Tannin is obtained from the bark and the strobils. Both the roots and the young shoots have been used in making baskets. A red to brown dye is obtained from the bark. Wood - soft, brittle, not strong, light, close and straight-grained, very durable in water. An important lumber tree, it makes a good imitation mahogany and is used for cheap furniture etc. A good fuel, it does not spark so can be used in the open, it also makes a high grade charcoal.

Charcoal: Used for fuel, drawing, deodorant, filter, fertilizer etc.

Dye: Plants that provide dyes.

Fodder: Food given to the animals (including plants cut and carried to them) rather than forage for themselves.

Fuel: Usually wood, plant materials that have been mentioned as being a good fuel.

Hedge: Plants that can be grown as hedges.

Pioneer: Plants, usually trees and shrubs, that can be used to reforest land.

Shelterbelt: Wind resistant plants than can be grown to provide shelter in the garden etc.

Soil stabilization: Plants that can be grown in places such as sand dunes in order to prevent erosion by wind, water or other agents.

Tannin: An astringent substance obtaied from plants, it is used medicinally, as a dye and mordant, stabilizer in pesticide etc.

Wood: A list of the trees and shrubs that are noted for having useful wood.

Agroforestry Services: Alley crop: Integrates annual crops with rows of perennials.

Agroforestry Services: Nitrogen: Plants that contribute to nitrogen fixation include the legume family – Fabaceae.

Fodder: Bank: Fodder banks are plantings of high-quality fodder species. Their goal is to maintain healthy productive animals. They can be utilized all year, but are designed to bridge the forage scarcity of annual dry seasons. Fodder bank plants are usually trees or shrubs, and often legumes. The relatively deep roots of these woody perennials allow them to reach soil nutrients and moisture not available to grasses and herbaceous plants.

Management: Coppice: Cut to the ground repeatedly - resprouting vigorously. Non-destructive management systems maintaining the soil organic carbon.

Management: Standard: Plants grow to their standard height. Harvest fruit, seeds, or other products. Non-Destructive management systems.

Regional Crop: These crops have been domesticated and cultivated regionally but have not been adopted elsewhere and are typically not traded globally, Examples in this broad category include perennial cottons and many nuts and staple fruits.

Agroforestry Services: Alley crop: Integrates annual crops with rows of perennials.

Agroforestry Services: Nitrogen: Plants that contribute to nitrogen fixation include the legume family – Fabaceae.

Fodder: Bank: Fodder banks are plantings of high-quality fodder species. Their goal is to maintain healthy productive animals. They can be utilized all year, but are designed to bridge the forage scarcity of annual dry seasons. Fodder bank plants are usually trees or shrubs, and often legumes. The relatively deep roots of these woody perennials allow them to reach soil nutrients and moisture not available to grasses and herbaceous plants.

Management: Coppice: Cut to the ground repeatedly - resprouting vigorously. Non-destructive management systems maintaining the soil organic carbon.

Management: Standard: Plants grow to their standard height. Harvest fruit, seeds, or other products. Non-Destructive management systems.

Regional Crop: These crops have been domesticated and cultivated regionally but have not been adopted elsewhere and are typically not traded globally, Examples in this broad category include perennial cottons and many nuts and staple fruits.

Carbon Farming: Plants that can be a critical part of the solution to climate problems. The Carbon Farming Solution - Eric Toensmeier.

Food Forest: Plants for Edible Forest Gardens and Food Forests.

Hedge: Hedge

Nitrogen Fixer: Plants that fix nitrogen in the soil

How it is grown

Landscape Uses:Border, Erosion control, Woodland garden. Prefers a heavy soil and a damp situation. Grows well in heavy clay soils. Tolerates very infertile sites. A very wind resistant tree with excellent establishment in severely exposed sites, it tolerates severe maritime exposure. The red alder is a very fast growing tree, even when planted in severe exposure, but it is short-lived, dying when 60 - 80 years old. 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. This is an important pioneer tree, quickly invading logged or burnt over sites, and providing ideal conditions for other trees to become established. A very ornamental tree. 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. Red alder has been estimated to fix as much as 300 kg of nitrogen per hectare. Special Features: Attracts birds, North American native, Inconspicuous flowers or blooms. In garden design, as well as the above-ground architecture of a plant, root structure considerations help in choosing plants that work together for their optimal soil requirements including nutrients and water. The root pattern is branching: a heart root, dividing from the crown into several primary roots going down and out .

Propagating it: Seed - best sown in a cold frame as soon as it is ripe and only just covered. Spring sown seed should also germinate successfully so long as it is not covered. 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. 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.

Best place to grow: Woodland Garden Canopy; Hedge; Bog Garden;

Habit: Tree

Hardiness: 6-8

Growth: Fast

Soil: Medium, heavy (clay)

Shade: Semi-shade, no shade

Moisture: Moist, wet

Things to keep in mind

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

Its other names

Local names

Synonyms

A. oregona.