Betula grossa long, yellow-brown, male catkins in early spring. . The species is considered closely related to the American birch "Betula lenta". Hardiness: RHS H4. Betula grossa Betula grossa, commonly known as Japanese cherry birch, is a species of birch native to Japan, where it grows naturally in mixed woodland on hill and mountain slopes in Honshu, Shikoku , and Kyushu. It was introduced to the West in 1896, but remains rare in cultivation. "Betula grossa" is conical in outline, but its most distinctive feature is its cherry-like bark, with horizontal stripes of reddish-grey becoming dark grey with age, exfoliating in thin
Alnus cordata with a very long season in leaf, from April to December in the Northern Hemisphere; they are alternate, cordate (heart-shaped), rich glossy green, 5–12 cm long, with a finely serrated margin. The slender cylindrical male catkins are pendulous, reddish and up to 10 cm long; pollination is in early spring, before the leaves emerge. The female catkins are ovoid, when mature in autumn 2–3 cm long and 1.5–2 cm broad, dark green to brown, hard, woody, and superficially similar to some conifer cones. The small winged seeds disperse through the winter, leaving the old woody, blackish 'cones' on the tree