Asian White Birch
Native to (or naturalized in) Oregon:
- Deciduous tree, may reach 30-65 ft (10-20 m) tall, light-open crown. Young twigs thin, dark gray to reddish, densely covered with white resin glands. Bud break is very early, some 3 weeks before other birches (Krüssmann, 1976). Leaves alternate, simple, triangular ovate, 4-6 cm long, base obliquely wedge-shaped (cuneate), apex short acuminate, margin coarsely serrate, 5-7 paired veins, deep green above, lighter below and with small brownish glands, otherwise both sides glabrous. Fruit catkins 3 cm long.
- Sun or light shade. Susceptible to bronze birch borer; see Dirr (1998, p. 134) for more information.
- Hardy to USDA Zone (4)5 Native to central and eastern Siberia, Manchuria, Korea and Japan. A few geographical varieties, the two most important appear to be:
- var. japonica - bark is pure white, twigs gladular-warty, leaves triangular-ovate, 4-7.5 cm long, to 6 cm wide, truncate at base or cordate, glabrous below or finely pubescent. Native to Japan, Manchuria and northern China. At one time the birch cultivar, ‘Whitespire’, was thought to be a selection of B. p. var. japonica, but it is now considered a selection of Betula populifolia.
- var. szechwanica - smaller, 15-40 ft (5-12 m) high, bark white or silvery-gray, or reddish, thin peeling; leaves triangular to ovate, to 6 cm long and 5 cm wide, base cuneate, apex short acuminate, margin irregularly serrate, tough to leathery, both side glabrous, densely glandular below (helps in identification, (Krüssmann, 1976); leaves persist until late fall. Native to western China.
- One rather winter hardy selection is Dakota Pinnacle® (USDA Zone 3)
- platyphylla: broad-leaved.
Portland, Oregon: Hoyt Arboretum