Rhododendron "Orange Ruffle", which is a Frank Abbott hybrid, has been determined to be a tretraploid 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
Tetraploid Rhododendron ""Orange Ruffle"
Source: John Abbott
John and Sally Perkins