{"slug":"alnus-rubra","scientific_name":"Alnus rubra","common_names":["Red alder","Oregon alder","Western alder"],"family":"Betulaceae","type":"broadleaf_deciduous","mature_height_m":25,"mature_spread_m":12,"growth_rate":"fast","lifespan_years":60,"hardiness_zones":[5,8],"sun":"full_partial","water":"medium","soil":"Wet to well-drained gravels, sands, clays and poor soils; fixes its own nitrogen","native_range":"Pacific coast from southeast Alaska through British Columbia, Washington and Oregon to central California, nearly always within about 200 km of the ocean, with inland pockets in Idaho and Montana.","description":"The largest North American alder and the Northwest's main hardwood: a fast, straight tree with smooth mottled gray bark (often painted with white lichen), serrated leaves with rolled-under edges that drop green, reddish catkins in late winter and small woody cones that hang on all winter. Root nodules fix nitrogen, so it rebuilds poor and disturbed soils and is widely used for streambank and mine-site restoration. It is short-lived and heart rot sets in after about 60 years.","care":"Plant in full sun or part shade in moist soil; it tolerates flooding and some drought once established. Little pruning is needed beyond removing dead wood in dormancy. Tent caterpillars, alder flea beetle and sawflies defoliate but rarely kill; avoid wounding the trunk, which lets heart rot in.","benefits":["nitrogen_fixing","fast_canopy","erosion_control","flood_tolerant","wildlife","birds","carbon"],"uses":["riparian","reforestation","timber","agroforestry","parks"],"cautions":["short_lived","allergenic_pollen"],"image_url":"https://upload.wikimedia.org/wikipedia/commons/a/a0/Yurok_Loop_Coastal_Trail_at_Redwood_NP.jpg","image_credit":"Wing-Chi Poon, CC BY-SA 3.0, via Wikimedia Commons","sources":["https://plants.ces.ncsu.edu/plants/alnus-rubra/","https://plants.usda.gov/plant-profile/ALRU2","https://en.wikipedia.org/wiki/Alnus_rubra"],"data_note":null,"updated_at":"2026-11-08T01:00:46.205Z","page_url":"https://treerm.org/trees/alnus-rubra","markdown_url":"https://treerm.org/trees/alnus-rubra.md","regions":[{"country":"CA","region":"BC","locality":null,"status":"native","note":null,"source_url":"https://plants.usda.gov/plant-profile/ALRU2"},{"country":"CA","region":"YT","locality":null,"status":"native","note":null,"source_url":"https://plants.usda.gov/plant-profile/ALRU2"},{"country":"US","region":"AK","locality":null,"status":"native","note":"Southeast Alaska.","source_url":"https://plants.usda.gov/plant-profile/ALRU2"},{"country":"US","region":"CA","locality":null,"status":"native","note":"Coast south to central California.","source_url":"https://plants.usda.gov/plant-profile/ALRU2"},{"country":"US","region":"ID","locality":null,"status":"native","note":"Inland pockets.","source_url":"https://plants.usda.gov/plant-profile/ALRU2"},{"country":"US","region":"MT","locality":null,"status":"native","note":"Northernmost Montana.","source_url":"https://plants.usda.gov/plant-profile/ALRU2"},{"country":"US","region":"OR","locality":null,"status":"native","note":null,"source_url":"https://plants.usda.gov/plant-profile/ALRU2"},{"country":"US","region":"WA","locality":null,"status":"native","note":null,"source_url":"https://plants.usda.gov/plant-profile/ALRU2"}],"license":"CC-BY-4.0"}