Rhododendron "Choptank" from Longwood Gardens has been determined to be a tetraploid using flow cytometry by
Dr. João Loureiro, Dr. Silvia Castro, José Cerca Oliveira, 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.
Ploidy testing indicates that the Choptank azaleas are tetraploids. Choptanks are most likely derived from only tetraploid species. Rhodendron atlanticum is the primary species in the background of most Choptank azaleas. Yellow Choptanks may contain Rhodendron austrinum.
Summary of Ploidy Levels
Tetraploid Rhodendron atlanticum,
Tetraploid Rhodendron austrinum,
Source: Longwood Gardens Accession Number: 1994-0808-C
John and Sally Perkins