'Rwain' X 'L'Engin' is a Tetraploid

Four seedlings of Rhododendron 'Rwain' X 'L'Engin', 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 'Rwain' (3X) X 'L'Engin' (4X), a triploid by a tetraploid produced a tetraploid indicating that triploid seed parent 'Rwain' acted as a tetraploid. In other words, the tetraploid seedlings of 'Rwain' X 'L'Engin' having 52 chromosomes most likely received 26 chromosomes from the triploid 'Rwain' and 26 chromosomes from the tetraploid 'L'Engin'.

Summary of Ploidy Levels

Triploid 'Rwain',
Tetraploid 'L'Engin',
Tetraploid 4 Seedlings of 'Rwain' X 'L'Engin'

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

'Antoon van Welie' is a Tetraploid

Rhododendron 'Antoon van Welie', which is a pre 1930 Endtz hybrid documented as 'Pink Pearl' x R. catawbiense, 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 'Antoon van Welie' has 'Broughtonii' and 'Pink Pearl' as a ancestors and 'Lydia' and 'Grand Slam' as descendants.

In the case of the tetraploid 'Antoon van Welie', a triploid crossed with a likely diploid produced a tetraploid indicating that unreduced meiosis occurred for either the triploid 'Pink Pearl' or the likely diploid R. catawbiense. In other words, 'Antoon van Welie' having 52 chromosomes either 1) received all 39 of 'Pink Pearl' chromosomes plus 13 from R. catawbiense or 2) received 26 from 'Pink Pearl' plus all 26 of R. catawbiense chromosomes.

Summary of Ploidy Levels

Triploid 'Broughtonii',
Triploid 'Lydia',
Triploid 'Pink Pearl',
Tetraploid 'Antoon van Welie',
Tetraploid 'Grand Slam',
Tetraploid 'Trude Webster'

Source: Whitney Nursery
Source: Van Veen Nursery

John and Sally Perkins

'L'Engin' is a Tetraploid

Rhododendron 'L'Engin', which is a Christian de la Sablière hybrid documented as 'Val d'Aulnay' X 'Lem's Cameo', 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.

In the case of the tetraploid 'L'Engin', a triploid crossed with a diploid produced a tetraploid indicating that unreduced meiosis occurred for either the triploid 'Val d'Aulnay' or the diploid 'Lem's Cameo'. In other words, 'L'Engin' having 52 chromosomes either 1) received all 39 of 'Val d'Aulnay' chromosomes plus 13 from 'Lem's Cameo' or 2) received 26 from 'Val d'Aulnay' plus all 26 of 'Lem's Cameo' chromosomes.

Summary of Ploidy Levels

Diploid 'Anna',
Diploid 'Lem's Cameo',
Diploid 'Norman Gill',
Diploid 'The Honorable Jean Marie de Montague',
Triploid 'Val d'Aulnay',
Tetraploid L'Engin

Source Marc Colombel

John and Sally Perkins