Rhododendron 'Julia Caroline', which is a Ned Brockenbrough hybrid documented as 'Horizon Lakeside' x 'Point Defiance', has been determined to be a triploid 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.
Summary of Ploidy Levels
Diploid 'Anna',
Diploid 'Horizon Lakeside',
Diploid 'Nancy Evans',
Diploid 'Norman Gill'
Diploid 'The Honourable Jean Marie de Montague',
Triploid 'Julia Caroline',
Tetraploid 'Marinus Koster',
Tetraploid 'Point Defiance'
Source: Whitney Nursery
John and Sally Perkins
