Alnus hirsuta, commonly known as Manchurian Alder, is a deciduous tree native to riparian zones, wetlands, and moist forest areas in East Asia, including regions of Siberia, Korea, and Japan. This species typically grows to a height of 15–20 meters (49–66 ft) and features smooth grey bark that remains unridged even in maturity. Its lifespan can extend from 60 to 100 years. The leaves are matte green, ovoid, and measure 5–11 centimeters (2–4+1⁄4 in) in length and 4–8 cm (1+1⁄2–3+1⁄4 in) in width. Manchurian Alder is notable for its early spring catkins; the male catkins are pendulous, measuring 5–10 cm (2–4 in) long, while the female catkins are smaller at 1.5 cm (5⁄8 in) long and 1 cm broad when mature in late autumn. The seeds are small, light brown, and feature a narrow encircling wing.

Manchurian Alder is valued for its ability to stabilize soil and improve nitrogen levels, making it useful for reforestation and ecological restoration projects. It is also cultivated for ornamental purposes in parks and gardens, particularly the ’Aurea’ cultivar with its attractive green-gold leaves, which has earned the Royal Horticultural Society’s Award of Garden Merit. The tree thrives in full sun and can adapt to a wide range of water conditions, from low to high, and is tolerant of various soil drainage types, including standing water. However, its shallow root system can lead to vigorous production of both stump and root suckers, which may be problematic in some settings.CC BY-SA 4.0