Rhododendron 'Rothenburg', which is a von Martin hybrid documented as 'Diane' 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
Diploid 'Diane',
Diploid 'Mrs. Lindsay Smith',
Triploid 'Rothenburg'
Source: Van Veen Nursery
John and Sally Perkins
