A tree ordinarily from 40 to 60, occasionally over 100 ft high, with a silvery-white trunk; branches pendulous at the ends; young wood not downy, but furnished with glandular warts. Leaves broadly ovate, sometimes rather diamond-shaped; 1 to 21⁄2 in. long, 3⁄4 to 11⁄2 in. wide; broadly wedge-shaped or truncate at the base, slenderly tapered at the apex, doubly toothed; not downy, but dotted with glands on both surfaces; stalk 1⁄2 to 3⁄4 in. long. Fruiting catkins 3⁄4 to 11⁄4 in. long, 1⁄3 in. wide, cylindrical; scales glabrous except on the margin; middle lobe the smallest.
Native of Europe (including Britain), especially of high latitudes; also of parts of N. Asia. This birch, with B. pubescens (q.v.), forms the B. alba of Linnaeus, but most authorities now concur in separating them. The species is easily distinguished from B. pubescens by the warts on the young branchlets and by the absence of down on all the younger vegetative parts. In the latter respect it differs from all the other cultivated birches except B. populifolia. It is a more graceful tree than the downy birch and is found on drier soils. (For timber value etc. see B. pubescens.)
A study of the cut-leaved birches of Scandinavia, by Nils Hylander, was published in Svensk Botanisk Tidskrift, Vol. 51, part 2, 1957.
f. crispa (Reichb.) Holmberg B. verrucosa or pendula var. laciniata of many authors, not Wahl. – This form has been confused with ‘Dalecarlica’, but has the leaves more regularly and less deeply cut; the basal lobes are not so finely tapered and do not arch backwards at the ends. Found wild in several localities in Scandinavia.
cv. ‘Dalecarlica’. – A very distinct tree, the leaves being lobed to within 1⁄8 to 1⁄4 in. of the midrib, the lobes themselves lanceolate, coarsely toothed, and with long slender points, the ends of the basal lobes curving backwards; leafstalks 1 to 13⁄4 in. long. Branches and leaves pendulous and the whole tree very elegant. (B. alba var. dalecarlica L. f.; B. a. var. laciniata Wahl.; B. pendula f. dalecarlica (L. f.) Schneid.)
According to Hylander (op. cit.) the original tree, described by the younger Linnaeus in 1781, grew at Lilla Ornäs in the province of Dalarna (Dalecarlia), where it was first observed in 1767. It was destroyed in a storm in 1887 but graft-wood had been taken from it some years earlier and the offspring planted in the Experimental Garden at Stockholm. From these, and hence from the type-tree, all the true Ornäs birches are descended by vegetative propagation. The cultivar name ‘Dalecarlica’ should be reserved for this clone. The botanical group name B. pendula f. dalecarlica (L. f.) Schneid. is available for other trees of similar character, but in fact only one has since been observed in Sweden, in the province of Smaland.
So far as is known the following specimens are of the true clone, which was introduced to Britain before 1885: Taymouth Castle, Perths., 90 × 51⁄4 ft, grafted at 1 ft (1961); Tittenhurst, Berks., 75 × 41⁄2 and 69 × 41⁄4 ft, both grafted at 5-6 ft (1963); Sheffield Park, Sussex, pl. 1910, 65 × 31⁄2 ft (1960); Madresfield Court, Worcs., 72 × 33⁄4 ft (1964); Royal Horticultural Society Gardens, Wisley, Surrey, 57 × 31⁄4 ft (1964).
cv. ‘Dentata Viscosa’. – A bushy, small tree of close, twiggy habit; branchlets and leaves very viscid; leaves closely set on the twig, 3⁄4 to 11⁄2 in. long, coarsely double-toothed or even small-lobed; leaf-stalks 1⁄2 in. long. This tree is no longer grown at Kew and must be very rare or even non-existent in British gardens, but is to be seen in continental collections and should be re-introduced. It was first distributed by Chenault of Orleans around 1912 as B. dentata viscosa pyramidalis.
cv. ‘Elegans’. – Branches hanging almost perpendicularly, leader erect. Bonamy’s nursery, Toulouse, around 1866.
cv. ‘Fastigiata’. – Branches erect-growing, the tree being of columnar habit and resembling a Lombardy poplar. First distributed by Simon-Louis Frères, before 1870. There is an example at Westonbirt, in Silkwood, measuring 71 × 31⁄4 ft (1964).
cv. ‘Gracilis’. – A small tree with finely cut leaves and drooping branches. The twigs are produced in clusters like elongated witches brooms. Origin unknown and perhaps not in cultivation here. There is a striking photograph of this birch in G. Kriissmann’s Handbuch der Laubgehölze, plate 60.
f. oycowiensis (Besser) Schneid. B. oycowiensis Besser – A rare native of S.E. Poland, found in a few localities near Krakow. It bears three to four leaves on the flowering twigs (usually two in the type) and the leaves are more equally toothed. It is of shrubby habit.
cv. ‘Purpurea’. – Leaves deep purple. The purple birch arose among seedlings raised in his own garden by a worker in Transon’s nursery, Orleans. He multiplied it by grafting and in 1873 sold the whole stock, which was apparently put into commerce under the epithets atropurpurea and foliis purpureis. But it was first described by André as B. vulgaris purpurea in Ill. Hort., Vol. 19, p. 199 (1872). It is figured in Rev. Hort. Belge, Vol. 4, p. 185 (1878).
cv. ‘Tristis’. – An elegant narrow-crowned tree with an erect leading shoot and drooping branches. Known since 1867. The same clone as ‘Elegans’?
cv. ‘Youngii’. Young’s Weeping Birch. – An elegant tree, good for small gardens. The branches are slender and perfectly pendulous, without a leading stem. If grafted on a high standard it makes a small mushroom-headed tree. If on its own stem it must be carefully trained.
B. obscura A. Kotula – This birch is found wild in a number of localities in Poland and in parts of Russia and Czechoslovakia. It resembles the silver birch and has the same chromosome number, the main mark of difference being the bark, which is dark grey or blackish brown. The leaves are more rounded in outline, more consistently wedge-shaped at the base, and darker green.
B. × koehnei Schneid. – This tree is of uncertain origin, but was thought by Schneider to be a hybrid between the silver birch and B. papyrifera. The type was grown in Späth’s nurseries as “B. cuspidata”. It is a graceful tree, which develops a white bark at an early age. There is an example 45 ft high in the Glasnevin Botanic Garden.