The RHS is the International Cultivar Registration Authority for the genus Rhododendron.
The International Rhododendron Register and Checklist, second edition, was published in November, 2004.
Where the data is available the individual entries contain details of parentage, names of all those involved with the raising, naming, introduction and registration of each plant, as well as whatever descriptive information can be found.
The text has been prepared by the International Registrar (Dr Alan Leslie) assisted by a small International Advisory Team consisting of: Jay Murray (USA), John Bond (UK), Charles Puddle (UK), Graeme Eaton (Australia), Michael Cullinane (New Zealand), Yukio Sasaki (Japan), Walter Schmalscheidt (Germany) and Albert De Raedt (Belgium).
Initial publication is in hard copy but it is intended that the data will be placed on the Society's website in due course. Annual hard copy supplements will continue to be issued.
Download registration forms here:
Application form to register a Rhododendron cultivar name
The RHS publishes The Rhododendron Register and Checklist 2004 and subsequent supplements, some of which are available from the link below.