Japan Flora: Much-branched, large to small shrub or small tree, with rather thick, gray-brown to dark gray gla- brous to glabrescent branches; leaves broadly ovate to ovate-orbicular, 6-10 cm. long, 4-7 cm. wide, abruptly short-acumi­nate to short-acute, rounded to shallowly cordate at base, with minute mucronate teeth, pale green and glabrous or nearly so beneath except for axillary tufts of hairs, the lateral nerves of 10 to 12 pairs, the petioles glabrous, 1-3 cm. long; staminate inflorescence from the terminal and upper lateral buds, the pistillate aments 3-5 in a group, loosely racemose on a short axis, arising from the buds below the staminate, the peduncles ascending, the pistillate aments broadly ellipsoidal, 1-1.5 cm. long.  June. High mountains, often ascending to the alpine zone;

Hokkaido, Honshu (centr. and n. distr.); common and very variable. Kamchatka, Sakhalin, Kuriles, Ussuri, and Korea.

Korea Flora: Deciduous shrub. Height 5m. Winter Buds and Stems: Elongate-ovoid, apex pointed, 7-15mm long, with 2 bud scales. Leaf scars triangular, kidney-shaped. Leaves: Ovate, elliptic, or elongate-ovate, apex acuminate, base rounded or broadly cuneate, 6-10(11)cm × (4)6-7cm, with linear serrations; upper surface glabrous; lower surface light green with numerous dots and pubescent along veins; about 10 pairs of veins. Petiole 10-25(30)mm long. Flowers: Male catkins in groups of 1-2(4), 4-8cm long, pendulous; female catkins ellipsoid, 1-1.5cm long, 4-5 catkins arranged in corymb-like clusters. Fruit and Seeds: Nuts 1.5-2.0cm × 1cm, ellipsoid; nutlets 2mm long, elliptic-ovoid, wings narrower than fruit width.

Flowering Period: May-June
Fruiting Period: September
Distribution: Throughout Northern Hemisphere; North Hamgyeong-do, North Pyeongan-do, northern Gangwon-do (up to Mt. Seorak), Ulleung Island (Korea)

Taxonomic Notes: Although Alnus fruticosa was traditionally known as a species distributed in northeastern China and Far Eastern Russia, recent studies consider it a subspecies (subsp. fruticosa) of the widely distributed European Alnus viridis (Chaix) DC., ranging from western North America through Far Eastern Russia. A. maximowiczii Callier ex C.K. Schneid., mainly distributed in Korea and Japan, was treated as A. viridis subsp. maximowiczii (Callier ex C.K. Schneid.) H. Ohba in recent Japanese flora (Ohba, 2006), but is considered a synonym of this species due to lack of distinguishing characteristics. Note that the name A. viridis subsp. maximowiczii (Callier) D.Love was already published in Taxon 17, 89 (1968).