This section is from the book "Handbook Of Hardy Trees, Shrubs, And Herbaceous Plants", by W. Botting Hemsley. Also available from Amazon: Handbook of hardy trees, shrubs, and herbaceous plants.
Trees or shrubs in which the scales of the female catkin are thin and deciduous, and usually trilobate. Stamens 2. The species are confined to the northern hemisphere. The name is that used by the ancients.
1. B. alba. Common Birch (fig. 214). - This graceful indigenous tree whose silvery white deciduous bark and slender branches render it so effective in a landscape, is represented by several varieties, differing mainly in the foliage from the ordinary form. But the first to claim our attention is B. a. pendula, the Weeping Birch, one of the most distinct and desirable of this class of trees, being of moderate size when fully developed. The foliage of the wild forms is extremely variable in size and outline, and there are some very distinct varieties in cultivation, such as B. a. laciniata, with deeply cut leaves, and B. a. popidifolia, the American variety, with large triangular acuminate leaves. This species has a very wide range through Europe, Northern Asia, and North America. The only objection to the Birch is its short life.
Fig. 214. Betula alba (Common Bi.ch).
B. nana is a mountain species occurring in Scotland, and having about the same general distribution as the last. There are also several North American hardy species, but they are too near in aspect to our indigenous species to be desirable except in a general collection. Some of them, however, are of larger stature and more valuable as timber trees.