Alnus rugosa (Du Roi) Sprengel. Phen: May-Jun; Jul-Aug. Hab: Braided streamhead seepage swamps (in VA), other seepy or saturated wetlands. Dist: NL west to SK, south to e. MD, w. VA, WV, IN, n. IL, ne. IA, MN, and e. ND.
Origin/Endemic status: Native
Taxonomy Comments: This taxon has often recently been treated as a subspecies of the European A. incana, but recent studies do not clearly show it as being most closely related to that taxon. A. incana occurs in nc. and ne. Eurasia. A. tenuifolia Nuttall occurs in w. North America, from AK south to CA and NM.
Synonymy: = G, W, Hardin (1971a), Hardin (1971a); = Alnus incana (L.) Moench ssp. rugosa (Du Roi) Clausen – FNA3, GrPl, K1, K3, K4, Mi, NE, NY, Pa, Va, Furlow (1990); = Alnus incana (L.) Moench var. americana Regel – C; = Alnus rugosa (Du Roi) Spreng. var. americana (Regel) Fernald – F; < Alnus incana (L.) Moench – Mi; > Alnus incana (L.) Moench – Il; > Alnus rugosa (Du Roi) Spreng. – Il; > Alnus rugosa (Du Roi) Spreng. var. rugosa – F