Betula michauxii
Betula cordifolia
bouleau de Michaux, Michaux's birch, Newfoundland dwarf birch
bouleau blanc, bouleau à feuilles cordées, heart-leaf paper birch, heartleaf birch, mountain paper birch, mountain white birch
of young trunks and branches dark reddish brown, close, in maturity reddish white to reddish tan or bronze, exfoliating in paper-thin sheets;
lenticels dark, horizontally expanded.
without taste and odor of wintergreen, moderately to densely pubescent, not conspicuously resin-coated, without large, warty, resinous glands.
glabrous to sparsely pubescent, often covered with conspicuous, warty, resinous glands.
blade obovate–reniform, with 2–3 pairs of lateral veins, 0.5–1 × 0.5–1.2 cm, base cuneate, margins deeply crenate-dentate, apex broadly rounded to nearly truncate;
surfaces abaxially usually glabrous.
blade narrowly ovate to ovate with 9–12 pairs of lateral veins, 6–10(–14) × 4–8 cm, base usually cordate, rarely rounded, margins coarsely or irregularly doubly serrate, apex short-acuminate, abaxially sparsely to moderately pubescent, sometimes velutinous or tomentose along major veins and in vein axils, covered with minute, resinous glands.
erect, short-cylindric, 0.5–1 × 0.5–0.8 cm, shattering with fruits in fall;
scales unlobed (lateral lobes sometimes present but greatly reduced), glabrous.
pendulous or nearly pendulous, cylindric, 2.5–5.5 × 0.6–1 cm, shattering with fruits in fall;
scales glabrous to moderately pubescent, lobes diverging proximal to middle, central lobe elongate, obtuse, lateral lobes ascending, shorter and slightly broader than central lobe.
with wings not apparent or reduced to narrow ridges.
with wings broader than body, broadest near summit, extended beyond body apically.
= 28, 56.
Betula michauxii
Betula cordifolia
This infrequent dwarf birch is distinguished from Betula nana mostly on the basis of its reduced infructescence scales and wetter habitat (J. J. Furlow 1984), characteristics that are also occasionally noted in B. nana. It perhaps might better be treated as a race of that species; in the absence of thorough study of this complex, however, it seems best to follow the traditional treatment (M. L. Fernald 1950c; J. Rousseau and M. Raymond 1950).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Betula cordifolia has been reported from Connecticut; I have not seen specimens.
In recent years Betula cordifolia has usually been treated as a variety of B. papyrifera, and perhaps it should be considered an ecological race of that species. It differs from B. papyrifera in polyploid level (diploid and tetraploid in B. cordifolia versus tetraploid, pentaploid, and hexaploid in B. papyrifera) and in vegetative characters, including the number of lateral veins of leaves and the color of bark (W. H. Brittain and W. F. Grant 1967; P. E. DeHond and C. S. Campbell 1989). In the Adirondacks, B. cordifolia and B. papyrifera occur in rather distinct ecological zones (B. cordifolia mostly above 800 m and B. papyrifera generally below this elevation). The species does not appear to occur as far west (Iowa) as stated by M. L. Fernald (1950).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
WildflowerSearch
iNaturalist
USDA Plants Database
Go Botany
MI Flora
MN Wildflowers
