Betula pumila
Betula uber
bog birch, bouleau nain, dwarf birch, glandular birch, low birch, scrub birch, swamp birch
Virginia roundleaf birch
without taste and odor of wintergreen, glabrous to moderately pubescent, with scattered small resinous glands, especially near nodes.
with taste and odor of wintergreen when crushed, glabrous, covered with small resinous glands.
blade elliptic, obovate, or nearly orbiculate (to sometimes reniform) with 2–6 pairs of lateral veins, 2.5–5(–7) × 1–5 cm, base cuneate to rounded, margins crenate to dentate, apex usually broadly acute or obtuse to rounded;
surfaces abaxially glabrous or slightly pubescent to heavily velutinous or tomentose, often with scattered 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, cylindric, 0.8–1.5(–2) × 0.8–1 cm, shattering with fruits in fall;
scales glabrous to pubescent, lobes diverging slightly distal to middle, central lobe narrow, elongate, lateral lobes shorter and broader, 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 slightly narrower than body, broadest near center, not extended beyond body apically.
with wings narrower than to as wide as body, broadest near summit, extended beyond body apically.
= 56.
Betula pumila
Betula uber
Betula pumila is sometimes treated (in part) as a variety of B. glandulosa Michaux, to which it is related at a subgeneric or sectional level. On the basis of morphology, however, it forms a cohesive and distinct entity (J. J. Furlow 1984). The two main varieties into which B. pumila is often divided (a more southern B. pumila var. pumila, with mostly pubescent, glandless leaves, and a more northern B. pumila var. glandulifera, with less pubescent, gland-bearing leaves) may represent geographic races; these are not well marked, however, and they do not hold up well when the complex is examined as a whole.
The Ojibwa used Betula pumila medicinally as a gynecological aid and as a respiratory aid (D. E. Moerman 1986).
(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.)
- Local floras:
BC, 
OR, 
WA - Local Web sites:
CalFlora, CalPhotos, 
Flora NW, 
Go Botany, 
IL Wildflowers, 
KS Wildflowers, 
MI Flora, 
MN Wildflowers, 
PNW Herbaria 
WildflowerSearch
iNaturalist (observations)
USDA Plants Database- LBJ Wildflower Center
- SEINet
- Plants of the World Online
- Encyclopedia of Life
- Wikipedia
- Google Image Search
