Publication: Proc. Roy. Irish Acad. 34: 55. 1919.
selected vouchers: WTU
Notes: FNA2: "Tsuga × jeffreyi (Henry) Henry was described from southwestern British Columbia and western Washington as a hybrid between T . heterophylla and T . mertensiana . Hybridization is rare, if it occurs at all, and it is therefore of little consequence (R.J. Taylor 1972). At the upper elevational limits of its distribution and under stressful conditions, T . heterophylla tends to resemble T . mertensiana , e.g., leaves are less strictly 2-ranked and stomatal bands on the abaxial leaf surfaces are less conspicuous than at lower elevations."