'Horizon Monarch' X 'Rwain' is a Triploid

One seedling of Rhododendron 'Horizon Monarch' X 'Rwain', which was raised by Marc Colombel, 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.

In the case of the triploid seedling of 'Horizon Monarch' (4X) X 'Rwain' (3X), a tetraploid by a triploid produced a triploid indicating that triploid pollen parent 'Rwain' acted as a diploid. In other words, the triploid seedlings of 'Horizon Monarch' X 'Rwain' having 52 chromosomes most likely received 26 chromosomes from the tetraploid 'Horizon Monarch' and 13 chromosomes from the triploid 'Rwain'.

Summary of Ploidy Levels

Triploid 'Rwain',
Triploid 1 Seedling of 'Horizon Monarch' X 'Rwain'
Tetraploid 'Horizon Monarch',
Tetraploid 3 Seedlings of 'Horizon Monarch' X 'Rwain'

Source Marc Colombel

John and Sally Perkins

'Horizon Monarch' X 'Rwain' is a Tetraploid

Three seedlings of Rhododendron 'Horizon Monarch' X 'Rwain', which were raised by Marc Colombel, have 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.

In the case of the tetraploid seedling of 'Horizon Monarch' (4x) X 'Rwain' (3X), a tetraploid by a triploid produced a tetraploid indicating that triploid pollen parent 'Rwain' acted as a tetraploid. In other words, the tetraploid seedlings of 'Horizon Monarch' X 'Rwain' having 52 chromosomes most likely received 26 chromosomes from the tetraploid 'Horizon Monarch' and 26 chromosomes from the triploid 'Rwain'.

Summary of Ploidy Levels

Triploid 'Rwain',
Triploid 1 Seedling of 'Horizon Monarch' X 'Rwain'
Tetraploid 'Horizon Monarch',
Tetraploid 3 Seedlings of 'Horizon Monarch' X 'Rwain'

Source Marc Colombel

John and Sally Perkins

'Gentle Giant' is a Tetraploid

Rhododendron 'Gentle Giant', which is a D. Sanders hybrid documented as 'Point Defiance' x 'Platinum Pearl', 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.

Rhododendron 'Gentle Giant' has as ancestors 'Broughtonii', 'Pink Pearl', 'Cynthia', 'Countess of Derby', 'Trude Webster', 'Platinum Pearl', 'Norman Gill', 'The Honourable Jean Marie de Montague', 'Anna', 'Marinus Koster', and 'Point Defiance'.

Both of the parents of 'Gentle Giant' have 'George Hardy' as an ancestor.

In the case of the tetraploid 'Gentle Giant', a tetraploid crossed with a triploid produced a tetraploid indicating that reduced meiosis most likely occurred for both parents. In other words, 'Gentle Giant' having 52 chromosomes received something similar to 26 chromosomes each from both the tetraploid 'Point Defiance' and the triploid 'Platinum Pearl'.

Rhododendron 'Gentle Giant' was also determined to be a tetraploid using flow cytometry by Dr. Thomas Ranney, J.R. Jones, and Nathan Lynch.

Summary of Ploidy Levels

Diploid 'Anna',
Diploid 'Norman Gill',
Diploid 'The Honourable Jean Marie de Montague',
Triploid 'Broughtonii',
Triploid 'Cynthia',
Triploid 'Pink Pearl',
Triploid 'Platinum Pearl'
Tetraploid 'Countess of Derby',
Tetraploid 'Gentle Giant',
Tetraploid 'Marinus Koster',
Tetraploid 'Point Defiance',
Tetraploid 'Trude Webster'

Source: Greer Gardens

John and Sally Perkins

'Grand Slam' is a Tetraploid

Rhododendron 'Grand Slam', which is a Harold Greer hybrid documented as 'Trude Webster' x 'Lydia', 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.

Rhododendron 'Grand Slam' has as ancestors 'Broughtonii', 'Pink Pearl', 'Cynthia', 'Countess of Derby', 'Trude Webster', 'Antoon van Welie', and 'Lydia'.

Both of the parents of 'Grand Slam' have 'Pink Pearl' as an ancestor.

In the case of the tetraploid 'Grand Slam', a tetraploid crossed with a triploid produced a tetraploid indicating that reduced meiosis most likely occurred for both parents. In other words, 'Grand Slam' having 52 chromosomes received something similar to 26 chromosomes each from both the tetraploid 'Trude Webster' and the triploid 'Lydia'.

Rhododendron 'Grand Slam' was also determined to be a tetraploid using flow cytometry by Dr. Thomas Ranney, J.R. Jones, and Nathan Lynch.

Summary of Ploidy Levels

Triploid 'Broughtonii',
Triploid 'Cynthia',
Triploid 'Lydia',
Triploid 'Pink Pearl',
Tetraploid 'Antoon van Welie',
Tetraploid 'Countess of Derby',
Tetraploid 'Grand Slam',
Tetraploid 'Trude Webster'

Source: Greer Gardens

John and Sally Perkins