Betula pendula
Betula uber
bouleau pleureur, European birch, European weeping birch, European white birch, silver birch, weeping birch
Virginia roundleaf birch
of mature trunks and branches creamy to silvery white, smooth, exfoliating as long strands;
lenticels dark, horizontally expanded.
dark brown, smooth, close.
pendulous;
twigs glabrous, usually dotted with small resinous glands.
with taste and odor of wintergreen when crushed, glabrous, covered with small resinous glands.
blade broadly ovate to rhombic with 5–18 pairs of lateral veins, 3–7 × 2.5–5 cm, base cuneate, rarely truncate, margins coarsely and sharply doubly serrate, apex acuminate;
surfaces abaxially glabrous to sparsely pubescent, covered with minute, resinous glands.
blade nearly orbiculate to broadly elliptic with 2–6 pairs of lateral veins, 2–5 × 2–4 cm, base rounded to cordate or truncate, margins irregularly serrate or dentate, apex broadly obtuse to rounded;
surfaces abaxially glabrous to sparsely pubescent, especially along major veins and in vein axils, often with scattered resinous glands.
erect to nearly pendulous, cylindric, 2–3.5 × 0.6–1 cm, shattering with fruits in fall;
scales adaxially sparsely pubescent, lobes diverging at middle, central lobe obtuse, much shorter than lateral lobes, lateral lobes broad, rounded, extended.
erect, ellipsoid-cylindric, 1–2 × 1–1.5 cm, shattering with fruits in fall;
scales glabrous, lobes diverging distal to middle, central lobe ascending, shorter than lateral lobes.
with wings much broader than body, broadest near center, extended beyond body apically.
with wings narrower than to as wide as body, broadest near summit, extended beyond body apically.
= 28, 56.
Betula pendula
Betula uber
The Eurasian weeping birch (Betula pendula) is extensively cultivated throughout the temperate range of the flora, and it has been known to persist or to become locally naturalized in several areas, particularly in the Northeast. In vegetative features it resembles B. populifolia Marshall, to which it is closely allied; it can easily be distinguished from the latter by its peeling bark, as well as by its mostly pubescent leaves with somewhat shorter, acuminate apices.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Of conservation concern.
Betula uber, described in 1918, was not seen again until its widely celebrated rediscovery in 1974 (P. M. Mazzeo 1974; C. F. Reed 1975; D. W. Ogle and P. M. Mazzeo 1976; D. J. Preston 1976). It is apparently allied to B. lenta (W. J. Hayden and S. M. Hayden 1984; T. L. Sharik and R. H. Ford 1984); whether it constitutes a separate species or simply mutant individuals of B. lenta is a matter of controversy. Seeds obtained from the original single extant population of 17 trees and grown at the U.S. National Arboretum have produced an apparent hybrid swarm of offspring varying in leaf characteristics from those of B. uber to those of B. lenta (with which it occurs).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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