Aroids
International Aroid Society
Bromeliads
Bromeliad Society International
Roses
Canadian Rose Society
http://canadianrosesociety.org/
Clematis
International Clematis Society
http://www.clematisinternational.com/
Cottage Gardens
Cottage Garden Society (UK)
http://thecottagegardensociety.org.uk/homepage
Geraniaceae
International Geraniaceae Group
https://www.geraniaceae-group.org/
Geraniums
International Geranium Society
http://www.internationalgeraniumsociety.com/
Hardy Plants
Hardy Plant Society (UK)
https://www.hardy-plant.org.uk/
Herbs
International Herb Association
Hibiscus
International Hibiscus Society
http://internationalhibiscussociety.org/
Palms
International Palm Society
Waterlilies and Water Gardening
International Waterlily and Water Gardening Society
Magnolias
Magnolia Society International