Alnus rubra, commonly known as Red Alder, is a deciduous broadleaf tree native to the moist coastal forests of western North America, including regions such as Alaska, Yukon, British Columbia, Washington, Oregon, California, Idaho, and Montana. It is the largest species of alder in North America and one of the largest globally, with mature trees typically reaching heights of 20 to 30 meters (66 to 98 ft) and forming a straight trunk with a narrow crown. The Red Alder’s leaves are ovate with a serrated margin, and it produces catkins which give way to small, woody cones. It flowers from February to April, with the male catkins being long and drooping and the female ones shorter and erect. The flowers are not particularly showy, but the tree is valued for its rapid growth and ability to fix nitrogen in the soil.

Red Alder is appreciated for its ecological benefits, such as improving soil fertility and providing habitat for wildlife. It is used in reforestation projects, erosion control, and occasionally as an ornamental tree in large spaces. It thrives in moist, well-drained soils and is often found in riparian zones, making it suitable for planting in swales and along stream banks. Red Alder requires full sun to part shade and moderate water, avoiding heavy, wet clay soils. It is important to plant Red Alder away from infrastructure to prevent root intrusion issues. While it is shade intolerant, it can adapt to a range of soil conditions provided they are well-drained.CC BY-SA 4.0