BETULA PUBESCENS, Common Birch
- Betula pubescens, Ehrhart, Beit. Naturk. vi. 98 (1793); Mathieu, Flore Forestière, 415 (1897); Winkler, Betulaceæ, 81 (1904).
- Betula tomentosa, Reitter and Abel, Abbild. Holzart, i. 17 (1790).
- Betula alba, Linnæus, Sp. Pl. 982 (1753) (in part); Roth, Tent. Fl. Germ. i. 404 (1788) ; Willkomm, forstliche Flora, 302 (1887); Schneider, Laubholzkunde, i. 116 (1904).
- Betula alba, Linnæus, var. pubescens, Loudon, Arb. et Frut. Brit. iii. 1691 (1838).
- Betula odorata, Bechstein, Diana, i. 74 (1797).
A tree, usually attaining 70 or 80 feet in height, and 5 or 6 feet in girth, occasionally larger. Branches ascending or spreading, branchlets usually not pendulous. Bark smooth, white, and papery, often peeling off in transverse shreds, with black triangular markings below the insertion of the branches ; thick and deeply furrowed at the base of old stems. Young branchlets covered with short, erect pubescence, often minute and only discernible with a lens, usually retained in the second year. Leaves (Plate 269, Fig. 1), 1½ inch to 2 inches long, ¾ inch to 1½ inch wide, rhomboid-ovate or ovate, usually cuneate at the base, acute or acuminate at the apex; margin ciliate and coarsely serrate; nerves, five or six pairs; upper surface with scattered pubescence; lower surface pubescent on the midrib and nerves ; petiole, ½ inch, pubescent and glandular.
Fruiting-catkins (Plate 269, Fig. 1), cylindrical, about 1 inch long, ⅓ inch wide, at first erect, afterwards pendulous, on long pubescent stalks; scales, puberulous, ciliate, with the central lobe more prolonged than is the case in B. verrucosa, and with the lateral lobes angular and usually erect, but occasionally recurved.’
In winter the twigs are slender, dark brown, densely covered with short, erect pubescence. Buds, 1⁄5 inch long, ovoid, rather blunt at the apex, viscid, with glabrous, ciliate scales.
Seedling.’—Cotyledons, about 1⁄6 inch long, oblong-ovate, obtuse, glabrous, with pubescent petioles, about 1⁄8 inch long. Caulicle short, pubescent, raising the coty- ledons above the ground. Stem pubescent and non-glandular, bearing primary leaves, which are alternate, ovate, cordate at the base, simply and coarsely serrate, and pubescent.
The birch,’ under ordinary conditions of growth, does not produce root-suckers ; however, when cut down, although coppice shoots are not given off from the stool, the roots give rise to numerous tomentose shoots, which bear leaves larger than
those of ordinary branches, cordate at the base, dentate in margin, and pubescent on both surfaces.
1 When the lateral lobes are recurved, the scales are similar in shape to those of B. verrucosa; and in such cases we may suspect a hybrid between the two species or an intermediate form. The pubescent stalks of the catkins and the puberulous scales are, however, apparently characteristic of B. pubescens.
? Cf, Lubbock, Seedlings, ii. 541, fig. 672 (1892).
3 Cf. Dubard, in Ann. Sc. Nat. xvii. 169, plate 2, fig. 4 (1903).
