BETULA. (according to some authorities, from Betu, its Celtic name; others give the derivation of the word as from batuo, to beat, the fasces of the Roman lictors, which were made of Birch rods, being used to drive back the people). Birch. ORD. Cupuliferæ. TRIBE Betuleæ. Ornamental, hardy (except where otherwise specified), deciduous trees or shrubs, allied to Alnus, having round, slender, often drooping branches, and the bark in most species in thin membranous layers. The flowers appear at the same time as the leaves. Male catkins cylindrical, lax, imbricated all round with ternate concave scales, the middle one largest, ovate; corolla none; filaments ten to twelve, shorter than the middle scale, to which they are attached. Female catkins similar, but more dense; scales horizontal, peltate, dilated outwards, three-lobed, three-flowered; corolla none. Nut oblong, deciduous, winged at each side. The Betulas are easily cultivated in any ordinary soil; but a light sandy loam suits them best. Most of the species are best increased by seeds, which ripen in September, and need to be dried, in order to prevent fermentation. They should be sown in March, in a sandy soil, the surface of which has been previously made perfectly level. They must be spread on the surface, and not covered with soil, but pressed down with the feet. When grown in quantities, beds 4ft. in width are preferred, with an alley of 1ft. between them. In early summer, if the weather be warm and dry, the beds should be shaded with branches. The young seedlings must be transplanted when a year old. The dwarfer kinds may be propagated by layering in the autumn. The numerous beautiful varieties are best increased by grafting or budding upon seedling stocks of the common kinds, the former being done in spring, and the latter in summer when the buds are ready. Those most useful as forest trees and for protection are quick-growing and very ornamental. The time of maturity of the Birch depends very much upon the soil and situation, but it seldom increases in size after it is thirty years old. The common species (B. alba) is one of the hardiest and most useful trees in cultivation, growing quickly, and withstanding exposure better than many others; consequently it is invaluable for skirting and nursing more tender subjects, and is especially desirable for clothing mountainous and exposed districts. It is also very beautiful and picturesque. It is the commonest tree throughout Russia, from the Baltic to the Eastern Sea, frequently monopolising gigantic forests. In Italy, it forms excellent forests up to 6000ft. altitude, and in our own Highlands of Scotland it occurs up to a height of 2500ft. In Greenland, although much reduced in size, it holds its own as the only arboreal vegetation.
FIG. 249. LEAVES AND CATKIN OF BETULA ALBA.
B. alba (white).* Silver, White, or Common Birch. fl. whitish. February and March. fr. brown, ripe in September and October. l. ovate, acute, somewhat deltoid, unequally serrated; autumnal tints rich yellow, scarlet, or red. A diminutive shrub in the extreme north, but a tree from 50ft. to 60ft. high in the middle regions. Britain. A most beautiful and invaluable forest tree, with a large number of varieties. See Fig. 249.
B. a. alba-purpurea (white and purple).* l. rich purple above, with a lustrous metallic hue, pale beneath. Branches with a sub-pendulous disposition. A very effective variety.
B. a. dalecarlica (Dalecarlian).* l. deeply pinnatifid, with the lobes toothed.
B. a. foliis-variegatis (variegated-leaved).* l. blotched with yellowish white.
B. a. laciniata pendula (pendulous and laciniate).* l. rather larger than the typical form, deeply laciniated, deep green, and decidedly pendulous. It appears there are two forms of this, but that known as Young's variety is the best.
B. a. macrocarpa (large-fruited).* Female catkins twice as long as those of the type.
B. a. pendula (pendulous).* A well-known tree, distinct from the species in having the shoots more slender, smoother, and pendulous.
B. a. pontica (pontic). l. somewhat larger than in the species, and the plant of more robust growth. (W. D. B. 2, 94.)
B. a. pubescens (downy). l. covered with hairs.
B. a. urticifolia (nettle-leaved).* l. deeply laciniated, serrated, and hairy. Several others, reputed as distinct, are mere forms of the typical B. alba.
B. Bhojpattra (Bhojpattra).* fl., female catkins erect, cylindrical, oblong; bracts smooth, woody, two-parted, blunt, much longer than the fruit, which has narrow wings. May. l. oblong-acute, with nearly simple serratures, somewhat cordate at the base; their stalks, veins, and twigs hairy; the bark is of a pale cinnamon colour. h. 50ft. Himalayas, 1840. This requires a sheltered position.
B. carpinifolia (Hornbeam-leaved). Synonymous with B. lenta.
B. daurica (Daurian).* fl., catkins whitish-brown, larger than those of the common Birch. February and March. l. ovate, narrow at the base, quite entire, unequally dentate, glabrous; scales of the strobiles ciliated on their margins; side lobes roundish. h. 30ft. to 40ft. Siberia, 1786. The variety parvifolia has smaller leaves than the type.
B. excelsa (tall). Synonymous with B. lutea.
B. fruticosa (shrubby).* fl. whitish-brown; female catkins oblong. February and March. l. roundish-ovate, nearly equally serrated, glabrous. h. 5ft. to 6ft. in moist situations, but much higher on mountains. Eastern Siberia, 1818. (W. D. B. 2, 154.)
B. glandulosa (glandular).* fl. whitish; female catkins oblong. May. l. obovate, serrate, quite entire at the base, glabrous, almost sessile; branches beset with glandular dots, glabrous. h. 2ft. Canada, 1816. A handsome little shrub. (F. D. 2583.)
B. lenta (pliant). fl. greenish-white. May to June. l. cordate, ovate, acutely serrated, acuminate; petioles and nerves hairy beneath; scales of the strobiles smooth, having the side lobes obtuse, equal, with prominent veins. h. 60ft. to 70ft. Canada to Georgia, 1759. SYN. B. carpinifolia. (W. D. B. 2, 144.)
B. lutea (yellow).* fl. greenish-white. May. l. 3½in. long, and 2½in. broad, ovate, acute, serrated; petioles pubescent, shorter than the peduncles; young shoots and leaves, at their unfolding, downy, but ultimately quite glabrous, except the petiole, which remains covered with fine short hairs; scales of the strobiles having the side lobes roundish. h. 70ft. to 80ft. Nova Scotia, 1767. SYN. B. excelsa.
B. nana (dwarf).* fl. whitish-green; catkins erect, stalked, cylindrical, obtuse; the barren ones lateral, and the fertile ones terminal; scales of the latter three-lobed, three-flowered, permanent. April and May. l. orbicular, crenate, reticulated with veins beneath. h. 1ft. to 3ft. Scotland, Lapland, Sweden, Russia, &c. A shrub with numerous branches, slightly downy when young, and beset with numerous little, round, firm, smooth, sharply crenated leaves, beautifully reticulated with veins, especially beneath; and furnished with short footstalks, having a pair of brown lanceolate stipules at their base. There is also a pretty variety named pendula, with drooping branches.
B. nigra (black).* The Black Birch. fl. greenish-white; female catkins straight, and nearly cylindrical, about 2in. long. May. l. rhomboid-ovate, doubly serrated, acute, pubescent beneath, entire at the base; scales of the strobiles villose; segments linear, equal. h. 60ft. to 70ft. New Jersey to Carolina, 1736. SYN. B. rubra. (W. D. B. 2, 153.)
B. papyracea (papery).* fl. greenish-white; female catkins on long footstalks, drooping; scales having the side lobes short, somewhat orbiculate. May to June. l. ovate, acuminate, doubly serrate; veins hairy beneath; petiole glabrous; the branches are much less flexible than those of the common Birch, and are more ascending. h. 60ft. to 70ft. North America, 1750. (W. D. B. 2, 152.)
B. p. fusca (brown). l. smaller than those of the type, and less downy.
B. p. platyphylla (broad-leaved).* l. very broad.
B. p. trichoclada (hairy-branched).* l. cordate. Branches extremely hairy, and twigs in threes.
B. populifolia (Poplar-leaved).* fl. greenish-white. April, May. l. deltoid, much acuminated, unequally serrated, quite smooth; scales of the strobiles having roundish side lobes; petioles glabrous. h. 30ft. Canada, 1750. This species, although very closely resembling B. alba, grows with less vigour, and does not attain so large a size. (W. D. B. 2, 151.)
B. p. laciniata (laciniated).* l. large, shining, and deeply cut.
B. p. pendula (pendulous).* Spray drooping, like that of B. alba pendula.
B. pumila (dwarf).* fl. whitish; female catkins cylindrical. May and June. l. roundish ovate, on long footstalks, densely clothed with hairs on the under surface. Branches pubescent, dotless. h. 2ft. to 3ft. Canada, 1762. A very beautiful kind, suitable for furnishing large rockeries, or planting on hill sides, or rocky ground. (W. D. B. 2, 97.)
B. rubra (red).* Synonymous with B. nigra.
BETULEÆ. A tribe of deciduous shrubs or trees. Perianth none, or bract-like; flowers monœcious, in catkins, in twos or threes. Fruit, a dry, compressed, lenticular, often winged, indehiscent nut. Leaves alternate, simple, stipulated. The genera are Alnus and Betula.
BI. In compound words, this signifies twice.
BIANCEA SCANDENS. See [Cæsalpinia sepiaria.]
BIARUM (an ancient name of a plant). ORD. Aroideæ. A genus of small, hardy, tuberous-rooted perennials, much more curious than pretty, allied to Sauromatum. This genus, according to Dr. Masters, differs from Arum in its spathe being tubular at the base, with the limb spreading. The female flowers have a distinct style, and the fruit contains only one ovule. They will thrive in any light, rich, well-drained soil, and may otherwise be treated similar to the hardy Arums. There are several other species besides those named, but they are not yet in general cultivation.
B. constrictum (constricted). A synonym of B. tenuifolium.
B. gramineum (grassy). A synonym of B. tenuifolium.
B. tenuifolium (slender-leaved).* fl., spathe dark brown-purple, reflexed in the upper part; spadix very long, subuliform. June. l. linear-lanceolate. h. 6in. South Europe, 1570. SYNS. B. gramineum and B. constrictum. (B. R. 512, under name of Arum tenuifolium.)