Alnus rhombifolia (White Alder) SE
Plant Description: This is a fast growing tree with a symmetrical canopy. It has horizontal branches with pendulous tips and attractive silver gray bark. The crown is a pyramidal shape in younger trees and becomes more oval with age. The green to yellow leaves are elliptic to oblong with finely serrated margins not rolled under. They are thicker and more leathery than other alders. Drooping greenish yellow male catkins, in clusters of 2-5, bloom before leaves emerge from mid winter to mid spring. The female catkins are born at the ends of branchlets. The tiny seeds within the cone lack papery wings. Also grows as a large shrub.
- Height: 50-70 ft
- Width: 30-40 ft
- Watering needs: Tolerant of seasonal flooding. Very intolerant of drought, the white alder needs summer watering to get established.
- Sun needs: Full sun to partial shade
- Soil needs: Grows in sand, clay, and tolerates poor drainage.
Landscape Use and Ecological Function: This native plant is commonly found along streams and rivers at low to mid elevations on both sides of the Cascades in Oregon. We recommend planting in woodland gardens.
White alder is a nitrogen fixing plant. It improves soil fertility and is often associated with disturbed sites. This plant also helps to create habitat and attract wildlife.
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