Rhododendron 'Trude Webster', which is a Harold Greer hybrid documented as 'Countess of Derby' X 'Countess of Derby', has been determined to be a tetraploid 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.
The hybridization work of Jim Barlup indicates that 'Trude Webster' is fertile in both directions when crossed with known and suspected polyploid elepidotes.
'Countess of Derby', which was determined to be a tetraploid, is the documented pollen parent of 'Anna Rose Whitney', which has been determined to be a triploid by the Coimbra based research team.
'Pink Pearl', which is the documented seed parent of 'Countess of Derby', was also determined to be a triploid by the Coimbra based research team.
'Cynthia', which is the documented pollen parent of 'Countess of Derby', was also determined to be a triploid by the Coimbra based research team.
The findings of the Coimbra based research team indicate 6 multi generational polyploid branches starting with the triploid 'Broughtonii', namely 1)'Broughtonii', 'Pink Pearl', 'Gomer Waterer', and 'Phyllis Korn', 2)'Broughtonii', 'Pink Pearl', 'Cynthia', 'Countess of Derby', and 'Anna Rose Whitney', 3)'Broughtonii', 'Pink Pearl', 'Cynthia', 'Countess of Derby', and 'Van',
4)'Broughtonii', 'Pink Pearl', 'Cynthia', 'Countess of Derby', and 'Lucky Strike',
5)'Broughtonii', 'Pink Pearl', 'Cynthia', 'Countess of Derby', 'Trude Webster', 'Platinum Pearl', and 'Gentle Giant' and 6)'Broughtonii', 'Pink Pearl', 'Antoon van Welie', 'Lydia', 'Trude Webster', and 'Grand Slam'.
Summary of Ploidy Levels
Triploid 'Anna Rose Whitney',
Triploid 'Broughtonii',
Triploid 'Cynthia',
Triploid 'Gomer Waterer',
Triploid 'Lydia',
Triploid 'Lucky Strike',
Triploid 'Pink Pearl',
Triploid 'Phyllis Korn',
Triploid 'Platinum Pearl',
Triploid 'Van',
Tetraploid 'Antoon van Welie',
Tetraploid 'Countess of Derby',
Tetraploid 'Gentle Giant',
Tetraploid 'Grand Slam',
Tetraploid 'Trude Webster'
Source: Greer Gardens
Source: Bob Fox
John and Sally Perkins
