Betula uber

(Ashe) Fernald

Rhodora 47: 325. 1945.

Common names: Virginia roundleaf birch
Conservation concernEndemic
Basionym: Betula lenta var. uber Ashe Rhodora 20: 64. 1918
Treatment appears in FNA Volume 3.

Trees, slender, to 10 m. Bark dark-brown, smooth, close. Twigs with taste and odor of wintergreen when crushed, glabrous, covered with small resinous glands. Leaf-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. Infructescences 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. Samaras with wings narrower than to as wide as body, broadest near summit, extended beyond body apically.


Phenology: Flowering late spring.
Habitat: Stream banks and adjacent flood plains in rich mesic forest
Elevation: 500 m

Discussion

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).

Selected References

None.

Lower Taxa

None.

"broadest" is not a number. "narrower" is not a number.

... more about "Betula uber"
John J. Furlow +
(Ashe) Fernald +
tanniferous +  and furrowed +
dark-brown +
exfoliating +
rounded +  and cordate +
Betula lenta var. uber +
2 (?) +  and 3 (?) +
slender +
staminate +  and pistillate +
solitary +  and in small racemose clusters +
ovoid +  and cylindric +
expanding +
Virginia roundleaf birch +
multibracteate +
pistillate +  and staminate +
expanding +
Stream banks and adjacent flood plains in rich mesic forest +
1 cm10 mm <br />0.01 m <br /> (2 cm20 mm <br />0.02 m <br />) +
ellipsoid-cylindric +
1 cm10 mm <br />0.01 m <br /> (4 cm40 mm <br />0.04 m <br />) +
1 cm10 mm <br />0.01 m <br /> (1.5 cm15 mm <br />0.015 m <br />) +
membranaceous +
10 cm100 mm <br />0.1 m <br /> (14 cm140 mm <br />0.14 m <br />) +
2 cm20 mm <br />0.02 m <br /> (5 cm50 mm <br />0.05 m <br />) +
2 cm20 mm <br />0.02 m <br /> (4 cm40 mm <br />0.04 m <br />) +
distal +  and middle +
dentate +  and serrate +
not obvious +  and defined +
membranaceous +
Flowering late spring. +
2(-3)-carpellate +
1-seeded +  and 2-winged +
extended +
crowded +  and imbricate +
deciduous +
(1-)3-lobed +
expanding +
not woody +  and leathery +
thicker +  and thin +
Conservation concern +  and Endemic +
2 (?) +  and 3 (?) +
nearly +  and distinct +
abaxially glabrous;sparsely pubescent +
Betula uber +
species +
excurrent +  and branching +
differentiated +
tanniferous +
light +, nearly white +  and reddish-brown +
soft +  and hard +