Propagation Methods and Distribution Potential of Eastern Hemlock, an Endangered Minnesota Conifer

Eastern hemlock (Tsuga canadensis) is a common native conifer in the eastern United States and is propagated and grown as an ornamental tree in the landscape. In Minnesota, however, it exists at the northwestern edge of its range and is listed as an endangered species with fewer than 50 trees and scattered seedlings found throughout the northeastern portion of the state. The Minnesota Landscape Arboretum has trees in its collection that were grown from seed produced by an extirpated eastern hemlock population near Mille Lacs Lake, MN. Through collaborations with the Minnesota Landscape Arboretum and the Minnesota Department of Natural Resources, we have potential to seed-propagate existing trees to preserve genetic diversity and integrity by introducing Minnesota-sourced seed into the landscape industry. This regionally adapted seed should lead to landscape plants that are better adapted to Minnesota’s climate. Our research combines genetic diversity information and clonal and seed propagation of native and cultivated populations to identify best practices for handling and distributing Minnesota-sourced Eastern hemlock seed and cuttings.  We measured the effect of four different auxin concentrations (0 ppm (control), 5,000 ppm IBA, 10,000 ppm IBA, and a 5,000 ppm IBA/5,000 ppm NAA combination) on winter hardwood cuttings taken in January 2015 from native-sourced Minnesota Landscape Arboretum accessions and will report these results. Additionally, in September 2014, cones were collected from two native remnant populations near Duluth, MN and four native-sourced accessions from the Minnesota Landscape Arboretum.  Estimated germination rates ranged from as low as 2% and 3% in seeds grown from native remnant populations to up to 28% in seeds grown from cultivated trees at the arboretum. Ultimately, establishment of best practices for propagation will inform both conservation and nursery industry distribution decisions.