American Ivy Society: A non-profit organization dedicated to preserving the genus Hedera through education and promotion. Site offers contact information, species photos with descriptions, a classification system, care instructions, article collection, membership details, and a question answering resource.
Hebe Society: International society based in Britain promoting the cultivation and conservation of hebes and other New Zealand native plants. Includes plant profiles and photos, FAQs, and links.
New Ornamentals Society: Devoted to the study of new and rare ornamental landscape plants. Includes an online source guide and plant encyclopedia.
Passiflora Society International: Dedicated to the preservation, study, and dissemination of Passiflora.
Scottish National Sweet Pea Rose & Carnation Society: Society home page with Sweet Pea and Rose trial results, flower show venue and reports.
The Geraniaceae Group: An international horticultural club interested in the species of all the genera of the Geraniaceae Family.
The International Geranium Society: Society for the enjoyment of plants in the geraniaceae family centered in California. Events, information about membership and the magazine, culture tip sheets, and a photo gallery.