Lowland Hemlock, Pacific Hemlock, Western Hemlock: Tsuga heterophylla (Synonym: Abies heterophylla) -
Black Hemlock, Mountain Hemlock: Tsuga mertensiana (Synonyms: Abies hookeriana, Abies mertensiana, Hesperopeuce mertensiana, Picea hookeriana, Tsuga crassifolia, Tsuga hookeriana, Tsuga mertensiana ssp. mertensiana) -