Gray Alder, Mountain Alder, Thinleaf Alder: Alnus incana ssp. tenuifolia (Synonyms: Alnus incana var. occidentalis, Alnus rugosa, Alnus tenuifolia) -
White Alder, California Alder: Alnus rhombifolia (Synonym: Alnus rhombifolia var. bernardina) -
Red Alder, Oregon Alder: Alnus rubra (Synonyms: Alnus oregona, Alnus oregona var. pinnatisecta, Alnus rubra var. pinnatisecta) -
Sitka Alder, Slide Alder, Wavy-leaved Alder: Alnus viridis ssp. sinuata (Synonyms: Alnus alnobetula, Alnus crispa ssp. laciniata, Alnus crispa ssp. sinuata, Alnus sinuata, Alnus sitchensis, Alnus viridis var. sinuata, Duschekia sinuata) -