The Alpine Garden Society
Aroidia Research
The American Conifer Society
The American Fern Society
The American Hemerocallis Society
The American Hosta Society
The American Iris Society
The Hardy Plant Society, U.K.
Massachusetts Horticultural Society
The New England Wildflower Society
The North American Rock Garden Society
The Pennsylvania Horticultural Society
The Royal Horticultural Society
The Scottish Rock Garden Society
The Sweet Violets Society
