Rhododendron "calendulaceum not", which appears to be a hybrid between Rhododendron flammeum and Rhododendron calendualceum, 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 Rhododendron flammeum,
Triploid Rhododendron "calendulaceum not",
Tetraploid Rhododendron calendualceum
Source: Arnold Arboretum Accession Number: 109-2007-Y
John and Sally Perkins
