Betula lenta
Betula glandulosa
cherry birch, sweet birch
bog birch, bouleau glanduleux, dwarf birch, dwarf resin birch, glandular birch, resin birch, scrub birch, shrub birch, swamp birch
of mature trunks and branches light grayish brown to dark brown or nearly black, smooth, close, furrowed and broken into shallow scales with age.
with taste and odor of wintergreen when crushed, glabrous to sparsely pubescent, usually covered with small resinous glands.
without taste or odor of wintergreen, essentially glabrous to sparsely pubescent, usually conspicuously covered with large, warty, resinous glands.
blade ovate to oblong-ovate with 12–18 pairs of lateral veins, 5–10 × 3–6 cm, base rounded to cordate, margins finely and sharply serrate or obscurely doubly serrate, teeth fine, sharp, apex acuminate;
surfaces abaxially mostly glabrous, except sparsely pubescent along major veins and in vein axils, often with scattered, minute, resinous glands.
blade mostly obovate to nearly orbiculate with 2–6 pairs of lateral veins, 0.5–3 × 1–2.5 cm, base cuneate to rounded, margins dentate-crenate, teeth obtuse to rounded, apex obtuse to rounded;
surfaces abaxially glabrous to moderately pubescent, especially along major veins and in vein axils, often covered with resinous glands.
erect, ovoid to nearly globose, 1.5–4 × 1.5–2.5 cm, usually remaining intact for a period after release of fruits in fall;
scales mostly glabrous, lobes diverging at or proximal to middle, central lobe short, cuneate, lateral lobes extended to slightly ascending, longer and broader than central lobe.
erect, cylindric, 1–2.5 × 0.5–1.2 cm, shattering with fruits in fall;
scales glabrous, lobes diverging distal to middle, central lobe elongate, lateral lobes ascending, somewhat shorter and broader than central lobe.
with wings narrower than body, broadest near center, not extended beyond body apically.
with wings narrower than body, broadest near summit, extended slightly beyond body apically.
= 28.
= 28.
Betula lenta
Betula glandulosa
Betula lenta is a dominant tree in the northern hardwood forests of the northern Appalachians and a valuable source of timber. It was formerly the chief commercial source of wintergreen oil (methyl salicylate), which is distilled from its wood. Betula lenta is most easily separated from B. alleghaniensis by its close bark and the glabrous scales of infructescences.
Native Americans used Betula lenta medicinally to treat dysentery, colds, diarrhea, fevers, soreness, and milky urine, and as a spring tonic.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Betula glandulosa is the characteristic dwarf birch of upland habitats throughout much of the mountainous west, occurring as well in dry open areas across the north. Where their ranges meet, B. glandulosa intergrades with both B. pumila Linnaeus and B. nana Linnaeus subsp. exilis (Sukaczev) Hultén, creating a confusing complex of intermediate forms. In the east, it reaches its southernmost limit on the subalpine slopes of high Adirondack peaks, including Mt. Washington, where it forms low sprawling thickets and scrubs.
Specimens of Betula glandulosa have been reported from the St. Lawrence Valley, but I have not seen them.
Wherever Betula glandulosa comes in contact with B. pumila, it forms a bewildering swarm of plants, known as B. ×sargentii Dugle, having intermediate states of most vegetative characters.
Plants intermediate between Betula glandulosa and B. nana subsp. exilis make up a continuum of forms linking the typical forms of Betula nana and B. glandulosa in parts of Alaska where the ranges of these species overlap. Wherever they occur in isolation, the species remain reasonably distinct and easy to identify. In southern Greenland, Betula glandulosa hybridizes with B. nana subsp. nana and with B. pubescens.
Betula ×eastwoodiae Sargent (= B. glandulosa × occidentalis) occurs in montane meadows and marshes in Alberta, British Columbia, Northwest Territories, Saskatchewan, Yukon, Alaska, Colorado, and Wyoming, where the range of the parents overlap.
Betula ×dugleana Lepage (= Betula glandulosa Michaux × B. neoalaskana Sargent) is common throughout Alaska and the Yukon, where the parent species frequently come into contact (E. Hultén 1941–1950, vol. 4; E. Lepage 1976).
Betula ×dutillyi Lepage [= Betula glandulosa Michaux × B. minor (Tuckerman) Fernald] is a putative hybrid that occupies the same general range as Betula minor. Like that species, however, it has not been studied experimentally. Careful examination of the entire complex to which this taxon belongs will be necessary before any of its parts can be truly understood. Betula ×dutillyi exhibits many of the same characteristics as B. minor, but it is slightly smaller in habit, and its leaves are smaller with somewhat blunter tips and more cuneate bases (E. Lepage 1976).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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