Silver Birch

Betula alba

COMMON NAMES

• Paper Birch
• Silver Birch
• White Birch

A well-known member of the catkin family of trees, recognized particularly for its silvery-white bark, peeling off in layers, along with its slender drooping branches. The leaves are broadly ovate, tapering to a fine point, toothed, but with a wide range of shapes around this pattern; they are smooth and shiny, but with minute glandular dots when young. The male catkins are drooping, 2-5 cm long, the female on short stalks but up to 15 cm long. The North American Betula lenta is medicinally close to B. alba.

Harvesting: the buds in March, the leaves in April-May, the bark and the sap also in spring. The sap is obtained by boring holes into the trunk and tapping the flow through a pipe into a vessel for up to 2 days, preserving the fluid with alcohol.

The leaves, buds and bark are dried in the usual way, though they take to being dried outside and this may be more efficient than using artificial heat. The leaves may be infused (adding a pinch of sodium bicarbonate aids extraction considerably), but the buds and bark will need varying degrees of decoction.

The mixture of volatile oils and resins has been found to be related in many ways to the oil of wintergreen (Gaultheria procumbens) used as an anti-inflammatory, both typically and systematically for arthritic and neuralgic conditions (however, although most commercial wintergreen oil is now, in fact, almost entirely obtained from distillation of the bark of the North American birch (B. lenta), this product does not actually exist in the original plant but is formed by interaction between constituents in the distilling process: thus there is no evidence of the presence of salicylates, so prominent in the oil, in the fresh sample). The effect of the oil is augmented by the saponins and flavonoids in a pronounced diuretic and urinary antiseptic action, and with bitter and other digestive stimulation.

PARTS USED

The young leaves, the bark, the sap and the leaf buds.

USES

The many usable parts of the birch have a similar action: much of their influence is concentrated on the kidneys and urinary system, and they are applicable to kidney stones in particular and other disorders of the urinary tract. However, there are other actions: for example there is a stimulation of bile flow and birch is also slightly sedative and notably anti-inflammatory. Overall, therefore, it is found useful in the treatment of many complex inflammatory conditions such as rheumatic, arthritic and dermatological problems.

It may be used in arthritic conditions both internally and topically (when distilled to produce the liniment-like oil of wintergreen preparation). One sign of an internal effect is the diaphoretic property of birch, which is such that sweating is induced when it is taken in large doses: this points to a particular application in those cases of acute rheumatic symptoms associated with fever or serum sickness. Along with the better flushing through of the tissues that this suggests, there is an action in reducing oedematous states, and one of its specific indications is for edema of renal and cardiac origins.

HABITAT AND CULTIVATION

The tree may be grown in larger gardens, but because of its shallow roots it should be at least 6 m away from any building; it is also susceptible to severe droughts for the same reason. Silver birch is found in woodlands throughout the whole northern hemisphere.

CONSTITUENTS

Silver birch contains: volatile oil and resin (together constituting 'empyreumatic oil of birch' -incl. betulin); saponins; flavonoids (mainly hyperoside); tannins; bitter glycoside.

USUAL DOSAGE

1-4 g dried leaves, bark or buds three times a day; 10-20 ml sap preserved with 20 per cent alcohol three times per day.

COMMENTS