Identifying characteristics:
This species was once classified as B. alba, or B. verrucosa.
As a young tree, it is graceful and pyramidal, becoming rounded or oval
and spreading, but retaining a pendulous habit. Leaves
are alternate, simple, and broadly oval-shaped (sometimes rhomboidal to
diamond-shaped). They are 1 to 3 inches long, glossy dark green and dotted
with glands on both surfaces. Margins are doubly serrate and the tree leafs
out early in spring. Fall color is yellow-green or a poor yellow, and the
leaves fall 3 or 4 weeks later than native birches. Flowers
are produced the previous season-male flowers in catkins in groups of 2
to 4, and female flowers in solitary, small, bracted spikes. The mature
seed catkin is pendulous and the fruit scales are slightly hairy on the
inner surface. The fruit is a small,
compressed, laterally-winged nutlet produced in 1.5-inch-long catkins. The
buds are imbricate, pointed and brownish-black. The whitish bark does not peel to the extent that the
paper birch (B. papyrifera)
does. The bark is brownish on young trees, becoming bright white on larger
branches and forms rough, fissured, black areas with age.
Similar species:
- Paper birch (B. papyrifera)
- gray birch (B. populifolia)
Ecology:
Distribution: Native to Europe (including Britain) and the high altitudes
of northern Asia, this birch also ranges north beyond the
Arctic circle. It is cultivated in Iowa for its attractive bark and graceful,
pendulous habit.
Habitat: Although this species will tolerate wet or dry soils, it grows best in moist, well-drained, sandy or loamy, soils. It is hardy from zone 2 to 7, and is a medium to fast-grower. Leaf miner and bronze birch borer are the most serious insect pests. The latter destroys the ornamental appeal of the tree, killing branches and even trunks by feeding on the inner bark. Trees grown outside their native habitats are usually more stressed, becoming more susceptible to pests and diseases. The European white birch is not as susceptible to bronze birch borer as is our native paper birch (B. papyrifera) .
Uses:
Wood: Birch wood is light-colored, heavy, strong, hard and
diffuse-porous.
Wildlife: Birches are of great value to northern wildlife. Hoofed browsers, snowshoe hares, beaver and porcupine feed on the wood, twigs or foliage. The seeds are eaten by redpoll and pine siskin, chickadees and rodents. Grouse feed on the catkins, buds and seeds.
Horticulture: Easy to transplant and reasonably adaptable, this is a very popular ornamental in the midwest and the eastern US in urban and suburban areas. Pruning should be avoided during late winter or early spring, as the tree will bleed excessively. Most birches with white bark are short-lived in cultivation, this species being no exception. 'Rocky Mountain Splendor' is a very hardy cultivar, able to withstand minus 40 F. It is a cross between B. pendula and B. occidentalis. 'Dalecarlica' is a coarsely-toothed cultivar with deeply-lobed leaves.
