Publication Date



Pollen; White spruce; Black spruce; Plant breeding


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.

First Page


Last Page




To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.