Betula L. (カバノキ)

Kamikanba (カミカンバ, 紙樺) * tentative translation (not in wide use), paper birch (American white birch / canoe birch)
Lifeform: deciduous tree < 30 m high
Distribution: boreal regions in North America (even in Washington State)
Habitat: a pioneer tree after various disturbances, including wildfire (森林火災) and logging

Varieties: regional populations
var. papyrifera
var. commutata (Regel) Fern. (western paper birch)
var. cordifolia (Regel) Fern. (mountain paper birch)
var. kenaica (W. H. Evans) Henry (Kenai birch)
var. neoalaskana (Sarg.) Raup (Alaskan paper birch)
var. subcordata (Rydb.) Sarg. (northwestern paper birch)

2. Leaves small up to 2 cm long, crenate, serrate, petioles short, densely fine-pubescent; wing of nutlets narrow

3. Leaves orbicular, with truncate or cordate base, often broader than long, crenulated all around; decumbent dwarf shrub ___ B. nana ssp. exilis, dwarf birch
3. Leaves obovate, with cuneate toothless base; upright shrub _____ B. glandulosa, shrub birch

2. Leaves large ___ B. nana × B. glandulosa

2. Leaves yellowish-green, especially below, with distinctly prolonged caudate apex _____ B. occidentalis
2. Leaves dark green, paler below, lacking caudate apex

3. Leaves triangular or diamond-shaped, with white hairs in margin; wings of nutlet as broad as body or narrower _____ B. kenaica
3. Leaves ovate, double-serrate; wings of nutlet broader than boty _____ B. papyrifera var. commutata

(Hultén 1968)