Betula - Birch
(Bet'ula)
DESCRIPTION: Betula is the botanical name for a group of deciduous (leaf-losing) trees and shrubs, commonly known as the Birches. They are natives of Europe, Asia and North America. Birches are very attractive, with their white or beautifully colored bark, which peels off in thin, papery fragments. Birch trees have simple (whole - not divided into separate pieces) leaves arranged alternately on the branch, with toothed and sometimes lobed edges. The leaves usually grow in pairs on short spur-like growths on the second-year branches. The flowers are produced in catkins in early spring before the leaves; male flowers grow in thin, pendant catkins and the female flowers are borne in smaller and rather erect catkins on growth of the previous season. Male and female flowers grow on the same tree and are noticeable, but are nothing spectacular. The fruits consist of a central axis to which many, little scales are attached. The seeds are winged and are scattered by the breeze. Birches grow naturally in cold climates and are very hardy; they withstand a substantial amount of exposure. B. lenta, the Black or Cherry Birch, has reddish-brown bark that has the smell and taste of wintergreen. The leaves grow from 2 to 4 inches long and are ovate to oblong in shape, with pointed tips and rounded or heart-shaped bases. They are dark green on top and a paler yellowish-green underneath. They give off the scent of wintergreen when crushed. This tree grows from 50 to 60 feet high. B. populifolia, the Gray Birch, is a small tree, only growing 20 to 30 feet high. The bark of this tree is chalky-white with dark spots below the branches. The leaves are triangular-ovate with long tapering, pointed tips and long leaf stalks. They grow from 2 to 3 inches in length and are shiny, dark green above and paler beneath. The edges are sharply and doubly toothed. This tree usually grows in groups of trunks - not just one central trunk. There are a few small, bushy types, such as B. nana and B. pumila, which may be planted in the rock garden. More Birches will be mentioned below in the varieties section. Many Birches have excellent wood that is used in the manufacture of furniture, plywood, cotton spools, brush backs, and many other things. The Karlean Birch from Finland is especially popular for making cabinets and small fancy objects. In some northern countries, Birch wood is used for fuel. Birch tar and oil used in the medical practice are obtained by distillation of the wood of the common Birch. The Black Birch, B. lenta, is one source of oil of wintergreen, which is used for medicinal purposes. This tree also yields sap, which is fermented to make Birch beer. The bark can be used for roofing houses and sheds and some is used for canoes. At one time, the bark was 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.
POTTING: Birches prefer moist, rich, fairly rocky ground, though they grow in a variety of soils. It is difficult to transplant large trees; so, while in nursery borders, they should be transplanted often until they can be placed in their permanent places. Planting can be done in the autumn or early spring. Old Birch trees do not handle pruning very well, therefore any pruning needed to produce a shapely tree should be carried out while the tree is young. Pruning, even of young trees, should not be done in the early months of the year because the tree will "bleed" (secrete sap) a lot. When pruning is done in the summer, sap doesn't exude from the wounds.
PROPAGATION: Seeds should be sown in the fall or spring, in containers filled with light, sandy soil and placed in a frame. Varieties that don't come true from seeds should be grafted on stocks on the most closely related kinds.
VARIETIES: B. lenta (Cherry Birch); B. lutea (Yellow Birch); B. nigra (River Birch); B. papyrifera (Paper or Canoe Birch); B. populifolia (Gray Birch); B. costata; B. Maximowicziana (Monarch Birch); B. mandshruica japonica (Japanese White Birch); B. pendula (European Birch); B. pendula dalecarlica; B. pendula fastigiata; B. pendula purpurea; B. pendula Youngii.
B. platyphylla 'Whitespire'
B. nigra 'Heritage'
Go see DICTIONARY OF BOTANICAL NAMES.
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