Rhododendron 'Will O The Wisp', which is a John Thornton hybrid documentd as Rhododendron minus X Rhododendron formosum, has been determined to be a diploid 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.
Rhododendron minus is a diploid species.
Summary of Ploidy Levels
Diploid Rhododendron minus,
Diploid 1 seedling from Rhododendron formosum X Rhododendron minus,
Diploid 'Will O The Wisp'
Source: John Thornton
John and Sally Perkins
