Rhododendron 'Gartendirektor Rieger', which is a Hobbie hybrid documented as 'Adriaan Koster' x R. williamsianum, has been determined to be a triploid using flow cytometry by
Dr. João Loureiro, Dr. Silvia Castro, José Cerca, and Mariana Castro
Plant Ecology and Evolution Group
Centre for Functional Ecology
Department of Life Sciences,
Faculty of Science and Technology,
University of Coimbra, Portugal.
Summary of Ploidy Levels
Triploid 'Gartendirektor Rieger'
Source: Jane Brooks
John and Sally Perkins
