Alnus rugosa var. occidentalis (Dippel) C.L. Hitchcock

Alnus rugosa var. occidentalis (Dippel) C.L. Hitchcock is a synonym sensu FNA Ed. Comm., 1997 of:

Alnus incana subsp. tenuifolia (Nuttall) Breitung, an accepted subspecies name sensu FNA Ed. Comm., 1997.