Alnus japonica, commonly known as Japanese alder, is a deciduous tree native to riparian zones, wetlands, and moist mountain forests in Japan, Korea, Eastern China, and Russia. It typically grows to a height of 50-65 feet (15-20 meters) with a broad, rounded crown. The tree’s bark is gray and smooth, becoming fissured with age. The leaves are oval-shaped with a serrated margin and a glossy green appearance. Japanese alder produces catkins; the male catkins are long and yellowish-brown, while the female catkins are shorter and green, maturing into small, woody cones that persist into winter. Flowering occurs in early spring before the leaves emerge, and while the flowers are not particularly showy, they are of interest to early-season pollinators.

Japanese alder is valued for its ability to thrive in wet conditions and is often used for reforestation projects and erosion control due to its fast growth rate and nitrogen-fixing abilities, which improve soil fertility. It is suitable for planting in riparian restoration projects and as a component in wetland gardens. In cultivation, it prefers full sun to part shade and tolerates a range of soil types, provided they are moist. It is relatively low-maintenance once established but may require additional water during dry periods.CC BY-SA 4.0