The late Professor Veitch laid finger on the only blot in this fair picture. Apples do not hang from rocks either in Tweedside or by Yarrow, but rowan berries do. It is a pity that Hamilton yielded so far to eighteenth century classicism as to introduce the conventional apple. The line would surely have run more smoothly—
"Fair hangs the rowan frae the rock."
But I have wandered away from the birch. Economically, this tree has hitherto been reckoned of indifferent value, though there is an inexhaustible demand for bobbins. Clogmakers, also, will make picturesque encampment among birches of suitable size, and pay a fair price for working up the stems.
Of the well-nigh imperishable bark no use is made in this country, except that chemists extract from it an antiseptic called pyrobetulin, used also in the preparation of glass for engraving. But Scandinavian farmers sheath their wooden houses with birch bark, which makes a durable, waterproof covering, with a beautiful silvery appearance very gratifying to eyes offended by the evil aspect of corrugated iron. In Russia, also, a fragrant oil is distilled from birch-wood, whence Russia leather derives its peculiar odour. Careful housewives should note that there is no kindling equal to birch bark, which blazes up almost as fiercely as celluloid.
Of late years, a new use has been found for birch, deserving attention from owners of land whereon this tree grows naturally. The small branches and spray are found serviceable in the preparation of steel plates, the price given at present being about 46s. a ton. The trees should be cut before the sap rises, else the bundles will lose weight in drying. In dealing with a birch wood for this purpose, the crop may be considered recurrent at short rotation; for numerous suckers arise from the roots after the tree is felled and grow very rapidly. It is to be noted with satisfaction that the well-nigh omnivorous rabbit cannot digest the young growths of birch; at least, it does not devour them wholesale.
The birch is very impatient of the shade of other trees. In its turn, although its delicate foliage might not be supposed to stop much light, its shade is very injurious to all other deciduous trees except the beech; a quality which causes one to wonder that such an experienced observer as P. J. Selby should have recommended it as a nurse for oak.[12] It is liable to be disfigured by the morbid growths popularly known as "witch's brooms." Authorities differ as to the cause of these fascinated bundles of twigs, some attributing them to the action of a fungus, Exoascus betulinus, others to the irritation brought about by a gall-mite (Eriophes rudis) attacking the buds. Probably both are contributory agents.
The Gaelic for birch is beith (pronounced "bey"), and may be recognised in numberless Scottish place-names, such as Drumbae, Auchenvey, Largvey, etc. The derivative beitheach (pronounced "beyoch"), signifying a birch wood, appears as Beoch in Ayrshire, Galloway, and Dumfriesshire.
Of exotic birches suitable for cultivation in the United Kingdom, there is a very complete collection in Kew Gardens. Among the North American species the black or cherry birch (Betula lenta) probably produces the best timber, but the most ornamental is the paper birch (B. papyrifera). The Japanese (B. maximowicsii) seems to promise better bulk than any other as a forest tree in this country.
