A tree 60 to 100 ft high in the wild, with a stem 6 to 9 ft in girth; bark nearly black, falling off in thick, rather small plates of irregular shape; young shoots dark brown, warted, at first downy. Leaves ovate, slender-pointed, rounded or widely tapered at the base, finely but irregularly toothed; 11⁄2 to 3 in. long, 1 to 13⁄4 in. wide; veins in nine to eleven pairs, slightly hairy above when young, more persistently so on the veins beneath; stalk 1⁄6 to 1⁄8 in. long, hairy. Male catkins 11⁄2 to 21⁄2 in. long; female catkins cylindrical, 1 to 11⁄4 in. long, 1⁄8 in. wide, usually solitary, rarely in pairs, stiff and erect at the fruiting state; scales three-lobed, the lobes linear-oblong, pointed, ciliate, the middle one twice as long as the side ones.
Native of Japan, Korea, and Manchuria; named and described by Regel in 1865; introduced to this country in 1914 by Wilson. He says: ‘This remarkable birch is rare in Japan and I saw it only on the wooded shores of Lake Chuzenji and in the ascent there from Nikko … it is a large tree with thick branches.’ It may usually be recognised by its blackish bark, erect female catkins, short leaf-stalks and minutely toothed leaves. It is succeeding very well at Kew. The wood is too heavy to float in water.
The present example at Kew, which measures 32 × 2 ft and was planted in 1915, shows very well the striking black bark that characterises this species.