Betula michauxii
Betula uber
bouleau de Michaux, Michaux's birch, Newfoundland dwarf birch
Virginia roundleaf birch
without taste and odor of wintergreen, moderately to densely pubescent, not conspicuously resin-coated, without large, warty, resinous glands.
with taste and odor of wintergreen when crushed, glabrous, covered with small resinous glands.
blade obovate–reniform, with 2–3 pairs of lateral veins, 0.5–1 × 0.5–1.2 cm, base cuneate, margins deeply crenate-dentate, apex broadly rounded to nearly truncate;
surfaces abaxially usually glabrous.
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, short-cylindric, 0.5–1 × 0.5–0.8 cm, shattering with fruits in fall;
scales unlobed (lateral lobes sometimes present but greatly reduced), glabrous.
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 not apparent or reduced to narrow ridges.
with wings narrower than to as wide as body, broadest near summit, extended beyond body apically.
Betula michauxii
Betula uber
This infrequent dwarf birch is distinguished from Betula nana mostly on the basis of its reduced infructescence scales and wetter habitat (J. J. Furlow 1984), characteristics that are also occasionally noted in B. nana. It perhaps might better be treated as a race of that species; in the absence of thorough study of this complex, however, it seems best to follow the traditional treatment (M. L. Fernald 1950c; J. Rousseau and M. Raymond 1950).
(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.)
WildflowerSearch
iNaturalist
USDA Plants Database
