Caplow, F. Botanist. February 2002. Washington Natural Heritage Program Department of Natural Resources, Olympia, WA.
Donovan, M. July 2001. Biological Information Coordinator. British Columbia (B.C.) Conservation Data Centre. B.C. Ministry of Sustainable Resource Management.
Douglas, W. George. Program Botanist. B.C. Conservation Data Centre, B.C. Ministry of Environment, Lands and Parks. Victoria, B.C.
Grushow, J. Professional gardener.
Kephart, S. Professor of Botany. Willamette University, Salem, Oregon.
McNeill, J. Director Emeritus, Royal Ontario Museum, Honorary Associate, Royal Botanic Gardens Edinburgh. Edinburgh, Scotland.
Morton, J.K. Professor Emeritus. University of Waterloo, Waterloo, Ontario.
