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