Mountain Alder
Alnus tenuifolia  Nutt.

The Mountain Alder is a shrub or small tree up to 20 feet tall of forest streams and has an extensive root system.  This usually shrubby alder is distinguished by its doubly toothed and sometimes lobed leaves that are rounded or heart-shaped at the base. It has 2 or more main stems with and smooth grey bark. The leaf edges are sharp pointed, with rather long teeth and appear wrinkled. Leaves are alternate, simple, ovate to oblong, up to 4 inches long, pointed or rounded at the tip, rounded or heart-shaped at the base, doubly toothed and sometimes shallowly lobed, paler on the lower surface, with hairy veins. It flowers in April through June. Male and female flowers borne separately but on the same plant; male spikes slender, drooping, up to 3 inches long; female spikes upright, up to 1/2 inch long; flowers open before the leaves unfold. The winter buds stalked and rounded and the seeds are borne in small dark brown woody cone like structures.  Nutlets up to 1/8 inch wide, with a narrow, membranaceous wing, are borne in a woody "cone."  Occurring mainly in the Douglas Fir zones, it sometimes grows along streams or mountain meadows in the higher elevations of the sagebrush/grass zone. This is the most common Alder in Idaho.

Medical Uses: The bark is astringent, emetic, haemostatic, stomachic and tonic. The bark also contains salicin[226], which probably decomposes into salicylic acid (closely related to aspirin) in the human body. This is used as an anodyne. The outer bark is astringent and is applied as a poultice to bleeding wounds, it also reduces swellings.

Planting:  Cuttings of mature wood should be taken as soon as the leaves fall in autumn, outdoors in sandy soil. Prefers a heavy soil and a damp situation, but rows well in heavy clay soils; however, it tolerates very infertile sites. Alder has a fast  rate of growth, but  is a short lived tree, which 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 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.

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