The authors acknowledge with thanks the help of Dr. Peter Ball, University of Toronto, Erindale College, in understanding character concepts, taxon delimitations, and for providing information from the developing Flora of North America treatment of this family. Thanks also to Dr. David Murray, University of Alaska, Dr. Bruce Ford, University of Manitoba, and Dr. Jeremy Bruhl, University of New England, Armidale, Australia for similar help. Molly MacCormac is thanked for assistance with photography both in the field and in the laboratory; Laurie Consaul for assistance in producing the maps; Jacqueline Madill for assistance with image management and Pam Whitmore for computer assistance. Polar Continental Shelf Project, the Nunavut Research Institute and Andrew Didiuk, Canadian Wildlife Service, are thanked for logistic support. The Canadian Museum of Nature and the Career Edge Internship Program are acknowledged for their financial support.