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

Belvedere House Park and Gardens - "A visitor attraction with visitor centre, shop and restaurant. Visitor information, events, function rooms."

Biltmore Garden Tour - "Forests and gardens, designed by landscape architect, Frederick Law Olmsted."

California Garden & Landscape History Society - "Background, activities and membership."

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."

Museum of Garden History - A few details of the Trust and a contact email.

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."

Southern Garden History Society - "Organization dedicated to the preservation and restoration of historic Southern U.S. gardens, and education about Southern landscape history. Information about membership, events, and publications."

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."