Betula papyrifera
Betula pubescens
bouleau blanc, bouleau à papier, canoe birch, paper birch, western paper birch, white birch
betula pubescens, downy birch, silver birch
of young trunks and branches dark reddish brown, smooth, in maturity creamy to chalky white or pale to (infrequently) dark brown, readily exfoliating in paper-thin sheets;
lenticels pale, horizontal, in maturity dark, much expanded, horizontal.
when young dark reddish brown, in maturity light reddish brown to tan or brownish or grayish white, smooth, rather close or readily exfoliating in paper-thin sheets;
lenticels pale, horizontal, in maturity dark, horizontally expanded.
without strong odor and taste of wintergreen, slightly to moderately pubescent, infrequently with scattered, small, resinous glands.
without taste and odor of wintergreen, usually covered with short bristly hairs.
blade ovate with 9 or fewer pairs of lateral veins, 5–9(–12) × 4–7 cm, base rounded, cuneate, or truncate, margins sharply to coarsely or irregularly doubly serrate or serrate-dentate, apex acute to short-acuminate;
surfaces abaxially sparsely to moderately pubescent, often velutinous along major veins and in vein axils, covered with minute, resinous glands.
blade ovate or rhombic-ovate, margins serrate, apex acute;
surfaces abaxially sparsely pubescent to velutinous, especially along major veins and in vein axils, without prominent resinous glands.
pendulous, cylindric, 2.5–5 × 0.6–1.2 cm, readily shattering with fruits in late fall;
scales pubescent to glabrous, lobes diverging at or proximal to middle, central lobe narrowly elongate, obtuse, lateral lobes about equal in length to central lobe but several times broader, strongly divergent, held nearly at right angles to axis.
with wings as broad as or slightly broader than body, extended nearly beyond body apically.
with wings equal to or somewhat broader than body, broadest near summit, extended beyond body apically.
catkins pendulous or subpendulous, cylindric, shattering with fruits in late fall;
scales puberulent to glabrous, often ciliate, lobes diverging at middle.
= 56, 70, 84.
Betula papyrifera
Betula pubescens
Betula papyrifera is a well-known tree of the northern forest with its paper-thin, white, peeling bark. The bark, which has a high oil content and is consequently waterproof, was used for a wide variety of building and clothing purposes by the American Indians, including the covering of the familiar birch bark canoe. It is still used for various purposes, including basketmaking, in Canada and Alaska. Variants having more or less close, dark brown bark (B. papyrifera var. commutata) occur locally throughout the wide range of this species; this characteristic appears to be largely environmentally caused. The species is an important successional tree, coming up readily after fires, logging, or the abandonment of cultivated land. The relatively soft, whitish wood is used extensively for such items as clothespins, spools, ice cream sticks, and toothpicks, as well as for pulpwood for paper.
Betula papyrifera is the state tree of New Hampshire.
Native Americans use Betula papyrifera medicinally in enemas, to shrivel the womb, to alleviate stomach cramps and pain, and as a tonic (D. E. Moerman 1986).
Betula ×sandbergii Britton is a fairly common hybrid, occurring where the ranges of the parents (B. papyrifera Marshall and B. pumila Linnaeus) come into contact. In most vegetative features it is intermediate between the parental conditions (K. E. Clausen 1963; C. O. Rosendahl 1928).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Subspecies 3 (2 in the flora).
Betula pubescens was used medicinally by the Cree for chafed skin, and by the Ojibwa as a seasoner in medicines and a component in a maple syrup mixture used to relieve stomach cramps (D. E. Moerman 1986, as B. alba).
Betula alba Linnaeus is a long-standing nomen ambiguum that had not been in use (until recently) because it included two taxa whose names had been widely adopted long ago. At this time a proposal to reject Betula alba is in press, and possibly a decision will be made before the end of the year (R. Brummitt, pers. comm.; Fred Barrie, pers. comm.)
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Leaf blade 3–4(–6) cm; twigs usually without conspicuous resinous glands; wing of samara 1–1.5 times as wide as body; trees usually with single trunk, persisting or escaped from cultivation. | subsp. pubescens |
1. Leaf blade 1–2.5(–3.5) cm; twigs ± glandular; wing of samara about as wide as body; native shrubs of sw Greenland. | subsp. tortuosa |
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