Betula pumila
Betula murrayana
bog birch, bouleau nain, dwarf birch, glandular birch, low birch, scrub birch, swamp birch
Murray's birch
of mature trunk and branches dark red to reddish brown, smooth, close;
lenticels pale, conspicuous, horizontally expanded.
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 to sparsely pubescent, 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 ovate with 7–10 pairs of lateral veins, 5–11 × 3–6 cm, base cuneate, margins sharply and obscurely doubly serrate, apex acute or only slightly acuminate;
surfaces abaxially sparsely pubescent to glabrous.
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, ovoid, 2–4 × 1.5–3 cm, remaining intact for a period after release of fruits in late fall;
scales sparsely pubescent to glabrous, lobes ascending, branching at middle, slightly unequal in length.
with wings slightly narrower than body, broadest near center, not extended beyond body apically.
with wings narrower than body, broadest near summit, not extended beyond body apically.
= 56.
= 112.
Betula pumila
Betula murrayana
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 murrayana is an octoploid derivative of Betula × purpusii (= B. alleghaniensis Britton × B. pumila Linnaeus) (B. V. Barnes and B. P. Dancik 1985). It is intermediate between B. alleghaniensis and B. pumila in most vegetative features, but in characters such as leaf size, it approaches B. alleghaniensis.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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