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Early Pollen Forcing In A White X Black Spruce Hybrid And Its Parental Species, Lawson L. Winton

Journal of the Minnesota Academy of Science

Viable pollen was successfully forced from winter-collected cuttings of white and black spruce, as well as of a hybrid of them. The natural time difference in flowering was overcame, thus providing a tool for interbreeding these species. During forcing, and naturally on the trees, pollen always shed from white spruce first, then the hybrid and finally from black spruce. Using departures from long-range weather averages, a heat-requirement difference was postulated for each species to account for the time difference in their flowering.