BETULA or BIRCH
Graceful Trees for Garden and Landscape Planting
Hardy, leaf-losing trees and shrubs which give their name to the family Betulaceae. Various kinds are found wild in Europe, Asia and North America and are distinguished by their graceful habit and white, or otherwise attractively colored bark, which peels off in thin, papery flakes. The flowers are in small catkins produced during spring, and are not very showy. Betula is the Latin name of the Birch.
Very Hardy Trees
As many Birches grow naturally in cold regions, some being found farther north than any other broad-leaved tree, they are very hardy and withstand a considerable amount of exposure. They are comparatively short-lived. They succeed in a great variety of soils.
When to Plant
The Birches do not transplant very well as large trees; therefore, while in nursery borders they should be regularly transplanted until they can be planted in permanent places. Planting can be carried out in fall or early spring. There are a few small bushy kinds, such as B. nana and B. pumila, that may be planted in the rock garden with success.
When to Sow Seeds
Whenever possible, the Birches should be increased by means of seeds, which may be sown in autumn or in spring, in light soil out of doors, or in boxes or flower pans filled with light sandy soil and placed in a frame. Varieties that do not come true from seed are grafted on stocks of the most closely related kinds.
Special Care Needed in Pruning
Special care is needed in pruning Birches. Old trees do not respond well to pruning; therefore enough pruning to encourage trees to grow into shapely specimens should be carried out while they are young. Moreover, pruning, even of young trees, should not be done in the early months of the year.
If branches are cut off before the leaves are developed, a good deal of “bleeding” takes place; if, however, pruning is carried out in summer, sap does not exude from the wounds and before the fall of the leaves the surface of the wound becomes hard enough to prevent the flow of sap.
Betula lenta, Cherry Birch, is a shapely tree with dark-brown bark and twigs that have a strong flavor of wintergreen. B. lutea, Yellow Birch, makes a handsome specimen up to 90 ft. tall and is conspicuous with its yellowish and silvery gray, curly bark. Betula nigra, River Birch, is remarkable for its shaggy reddish-brown bark; it thrives in moist ground. Betula papyrifera, Paper or Canoe Birch, may grow to 100 ft. or more and is very handsome; it has snowy white, flaky bark. B. populifolia, Gray Birch, is a small, graceful tree, short-lived but useful for poor, dry soil. It is often seen in clump form.
Betula costata is a graceful Asiatic tree to 90 ft. tall, with small, narrow leaves and white, flaky bark. B. Maximowicziana, Monarch Birch, from Japan, makes a tall vigorous tree with large leaves and long catkins; the bark is orange-gray and flaky. Betula mandshruica japonica, Japanese White Birch, somewhat resembles the American Paper Birch but is smaller; its silvery white bark shows orange beneath when it peels.
Betula pendula, European Birch, is a handsome tree with its white bark and graceful habit. Several varieties are grown. B. pendula dalecarlica has deeply lobed leaves on pendulous branches; B. pendula fastigiata is of narrow, upright form; B. pendula purpurea has purple leaves; and B. pendula Youngii forms a spreading head with slender, pendulous branches.
The wood of various kinds of Birch is in demand for furniture, plywood, cotton spools, brush backs, and a number of other purposes, and a finely figured kind from Finland, known as Karlean Birch, is popular for cabinets and small fancy articles. In some northerly countries Birch wood is much sought for fuel. Birch tar and oil used in medical practice are obtained by distillation of the wood of the common Birch; the North American Birch, B. lenta, is one of the sources of oil of wintergreen, which is used for medicinal purposes. From the sap of Birch an intoxicating liquor can be prepared, while the bark, which is very long lasting, is sometimes used for roofing houses and sheds and that of some kinds is used for canoes. Birch bark was at one time widely used by the North American Indians for making fancy articles, and pictures were painted on its surface. Bark has also been used for writing paper.