'Phyllis Korn' x 'Trude Webster' is a Pentaploid

Two seedlings of Rhododendron 'Phyllis Korn' x 'Trude Webster', which is a Jim Barlup hybrid, have been determined to be a pentaploid 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 pentaploid seedlings of 'Phyllis Korn' (3X) x 'Trude Webster' (4X), a triploid by a tetraploid produced a pentaploid indicating that the triploid seed parent 'Phyllis Korn' was most likely unreduced. In other words, the pentaploid seedlings of 'Phyllis Korn' x 'Trude Webster' having 65 chromosomes most likely received 39 chromosomes from the triploid 'Phyllis Korn' and 26 chromosomes from the tetraploid 'Trude Webster'. Considering the parents are a triploid and a neotetraploid, meiosis may not be normal for either parent.

Summary of Ploidy Levels

Triploid 'Phyllis Korn'
Tetraploid 'Trude Webster',
Pentaploid 2 Seedlings of 'Phyllis Korn' x 'Trude Webster'

Source: Jim Barlap

John and Sally Perkins

'Hollandia' is a Tetraploid

Rhododendron 'Hollandia', which is a 1896 Koster Ghent hybrid documented as Rhododendron luteum x Rhododendron molle ssp. japonicum, 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.

Summary of Ploidy Levels

Diploid Rhododendron molle
Diploid 'Miniatum Floribundum',
Triploid 'Aida',
Triploid 'Bronze Unique',
Triploid 'Croceum Tricolor',
Triploid 'Daviesii',
Triploid 'Deep Rose',
Triploid 'Freya',
Triploid 'Gloria Mundi',
Triploid 'Il Tasso',
Triploid 'Josephine Klinger',
Triploid 'Phebe',
Triploid 'Phidias',
Triploid 'Pontica Album',
Triploid 'Van Houttei Flore Pleno',
Triploid 'Velasquez',
Tetraploid Rhododendron luteum,
Tetraploid 'Admiraal De Ruyter',
Tetraploid 'Altaclerensis',
Tetraploid 'Ariel',
Tetraploid 'Beaté Céleste',
Tetraploid 'Bijou des Amateurs',
Tetraploid 'Bouquet de Flore',
Tetraploid 'Cardinal,
Tetraploid 'Comte de Flandre',
Tetraploid 'Corneille',
Tetraploid 'Directeur Charles Baumann',
Tetraploid 'Durante Alle',
Tetraploid 'Electum',
Tetraploid 'Eugénie',
Tetraploid 'Fénelon',
Tetraploid 'Flameola Incarnata',
Tetraploid 'Héroine Plena,
Tetraploid 'Heureuse Surprise',
Tetraploid 'Hollandia',
Tetraploid 'Hora',
Tetraploid 'Ignacea',
Tetraploid 'Igneum Novum',
Tetraploid 'Il Tasso',
Tetraploid 'Jenny Lind',
Tetraploid 'Juliana Nova',
Tetraploid 'Julius Caesar',
Tetraploid 'Leibuir',
Tetraploid 'Lelia',
Tetraploid 'Madame Gustave Guillemot',
Tetraploid 'Marie Verschaffelt',
Tetraploid 'Minerva',
Tetraploid 'Nancy Waterer',
Tetraploid 'Oscar I',
Tetraploid 'Perfecta',
Tetraploid 'Raphael de Smet'

Source: Azaleatuin

John and Sally Perkins

('Voluptuous' x 'Phipps Yellow') #3 is a Triploid

Rhododendron ('Voluptuous' x 'Phipps Yellow') #3, which is a Werner Brack hybrid, 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.

In the case of triploid ('Voluptuous' x 'Phipps Yellow') #3, a diploid crossed with a diploid produced a triploid indicating that unreduced meiosis most likely occurred for one of the diploid parents. In other words, ('Voluptuous' x 'Phipps Yellow') #3 having 39 chromosomes most likely received 13 from one diploid parent and 26 chromosomes from the other diploid parent.

Summary of Ploidy Levels

Diploid 'Phipps Yellow',
Diploid 'Voluptuous',
Triploid ('Voluptuous' x 'Phipps Yellow') #3

Source: Werner Brack

John and Sally Perkins

'Margaret Abbott' is a Tetraploid

'Margaret Abbott' (Frank Abbott) [4x]
Rhododendron prinophyllum [2x] X Rhododendron calendulaceum [4x]
Spring 2009 Saxtons River, VT
S and J Perkins

Rhododendron 'Margaret Abbott', which is a Frank Abbott hybrid documented as Rhododendron prinophyllum X Rhododendron calendulaceum, has been determined to be a tetraploid 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.

Rhododendron 'Margaret Abbott' was named by Frank to honor his wife. Frank was amazed he crossed a pink with a yellow to produce this lone fragrant ruffled white flower with a yellow flare. See A Love Affair With A Flower by Marge Runnion. See Frank Abbott's Village of Azaleas by John and Sally Perkins.

Notice in the image above on the flower facing forward, 'Margaret Abbott' has, at the end of the stamens, tagged anthers, such anthers rarely appear on a deciduous azalea. 'Margaret Abbott' is known to be partially seed fertile but does not appear to have viable pollen.

Notice, also, for 'Margaret Abbott' that the diploid is the seed parent and the tetraploid is the pollen parent. For deciduous azaleas, diploids usually accept pollen from tetraploids but tetraploids usually reject pollen from diploids. See Rules of Engagement by John and Sally Perkins.

In the case of the tetraploid 'Margaret Abbott', a diploid crossed with a tetraploid produced a tetraploid indicating that unreduced meiosis may have occurred for the diploid seed parent. In other words, 'Margaret Abbott' having 52 chromosomes received something on the order of 26 chromosomes from the diploid Rhododendron prinophyllum and 26 chromosomes from the tetraploid Rhododendron calendulaceum. See Unreduced Meiosis. See Ploidy of Deciduous Azaleas Species.

In every other case we have tested where a diploid deciduous azalea is crossed with a tetraploid deciduous azalea, the resulting offspring have been triploids having 39 chromosomes receiving 13 chromosomes from the diploid seed parent and 26 chromosomes from the tetraploid pollen parent. See 2X4 for Deciduous Azaleas. See Normal Meiosis.

Natural interactions of diploid deciduous azalea species and tetraploid diploid deciduous azalea species do occur in places such as Audra State Park. Plants that appear to be interploidy hybrids have tested as triploid and tetraploid. The ploidy results for 'Margaret Abbott' indicated that unreduced gametes of the diploid seed parent may be one of the mechanism causing tetraploids to be produced by diploid X tetraploid interaction. See Audra State Park: Ploidy Haven. See Rhododendron prinophyllum by Elizabeth Carlhian. See Rhododendron arborescens by Susan Clark. See Rhododendron calendulaceum by Joe Bruso.

The hybridizers of the Ghents, including some done by Ed Mezitt, the Rusticas, and the Northen Lights series crossed diploid and tetraploid deciduous azaleas. See Ghent. See Rustica. See Mezitt.

For large leaf elepidote hybrid Rhododendrons we have discovered several instances where a diploid X tetraploid results in tetraploids as well as triploids and diploids. For instance, Rhododendron 'Horizon Monarch', which is a Ned Brockenbrough hybrid documented as 'Nancy Evans' x 'Point Defiance', has been determined to be a tetraploid. 'Nancy Evans' has been determined to be a diploid and 'Point Defiance' has been determined to be a tetraploid. See 2X4 for Large Leaf Elepidotes. See 4X2 for Large Leaf Elepidotes.

For large leaf elepidote hybrid Rhododendrons we have discovered fertile triploids and the offspring of these triploids can be tetraploids. For instance, Rhododendron 'Countess of Derby', which is a 1913 Henry White hybrid documented as 'Pink Pearl' x 'Cynthia', has been determined to be a tetraploid. Both 'Pink Pearl' and 'Cynthia' have been determined to be triploids. See It is 1913 So What Do You Do? by John and Sally Perkins. See Fertile Triploids. See Pink Pearl.

For large leaf elepidote hybrid Rhododendrons we have discovered tetraploids can produce diploid offspring in the first generation. See Super Reduced Meiosis.

Although there are no known polyploid elepidote species, many elepidote hybridizers, including Barlup, Bones, Brack, Briggs, Brockenbrough, Broughton, Bruns, Colombel, Croux and Fils, de la Sablière, Endtz, Evans, Felix and Dijkhuis, Fujioka, Greer, Gehnrich, Hachmann, Hartman, Heinje, Henny and Wennekamp, Hobbie, Kavka, Kehr, Korn, Koster, Lem, Loder, Lofthouse, Mangles, Markeeta, McCullough, Mossman, Murcott, Naylor, Patterson, Pearce, Rabideau, Sanders, Schannen, Seabrook, Standish and Noble, Stead, Stockman, Thornton, vanNes, VanVeen, von Martin, Walton, Waterer, White, Whitney, Wilson, and Woodward have worked with or produced ployploid elepidotes hybrids and in some cases are best known for these polyploid hybrids.

Clarence Towe aided us in confirming that the plant pictured above is 'Margaret Abbott'.

To see a poster on the ploidy results (Click on the poster image to enlarge):

Ploidy Research Poster by José Cerca Oliveira.

To see the research team:

Research Team of Dr. João Loureiro, Dr. Silvia Castro, José Cerca Oliveira, and Mariana Castro.

To see other images of Frank Abbott's azaleas visit the following:

Abbott Azaleas by S & J Perkins.

The "In The Collections" web page of the Arnold Arboretum includes a reference to our ploidy research.

Summary of Ploidy Levels

Diploid Rhododendron molle,
Diploid Rhododendron prinophyllum,
Diploid 'Frank Abbott',
Diploid "Jane Abbott" (grex),
Diploid 'Nancy Evans',
Triploid 'Cynthia',
Triploid 'Pink Pearl',
Tetraploid Rhododendron calendulaceum,
Tetraploid 'Countess of Derby',
Tetraploid 'Horizon Monarch',
Tetraploid 'Margaret Abbott',
Tetraploid 'Point Defiance'

Source: John Abbott

Ploidy Results by Groups

Rhododendron Species,
Diploid Deciduous Azaleas,
Triploid Deciduous Azaleas,
Tetraploid Deciduous Azaleas,
Diploid Large Leaf Elepidotes,
Triploid Large Leaf Elepidotes,
Tetraploid Large Leaf Elepidotes,
Diploid Lepidotes,
Triploid Lepidotes,
Tetraploid Lepidotes,
Diploid Everegreen Azaleas,
Triploid Evergreen Azaleas,
Diploids,
Triploids,
Fertile Triploids,
Tetraploids,
Ghents,
Northern Lights, and
Rusticas

The following people and organizations donored samples for this reasearch:

John Abbott,
Vivian Abney of East Fork Nursery,
Arnold Arboretum,
Audra State Park,
Bartlett Arboretum,
Jim Barlup,
Bruce Clyburn,
Jane Brooks,
Joe Bruso,
Werner Brack,
Ned Brockenbrough,
Canobie Lake, NH,
Dick Cavender,
Connecticut College Arboretum,
Marc Colombel,
Mike Creel,
Al Fitzburg,
Robert Fox,
Harold Greer of Greer Gardens,
George Hibben,
Highstead Arboretum,
Don Hyatt,
Lindy Johnson of Appalachian Native Plants,
Richard Jaynes of Broken Arrow Nursery,
Doug Jolley,
Fred Knippel,
Longwood Gardens,
Ron Miller,
Dick Murcott,
Planview Nursery,
John and Sally Perkins,
Ron Rabideau of RareFind Nursery,
Ellie Sather of Whitney Gardens,
Stoddard Blog, NH,
John Thornton,
Hendrik Van Oostand of Azaleatuin,
Kathy Van Veen of Van Veen Nursery

John and Sally Perkins

'Markeeta’s Flame' is a Triploid

Rhododendron 'Markeeta’s Flame', which is Markeeta Nursery hybrid documented as 'Loderi Venus' x 'Anna', 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 triploid 'Markeeta’s Flame', a diploid crossed with a diploid produced a triploid indicating that unreduced meiosis most likely occurred for one of the diploid parents. In other words, 'Markeeta’s Flame' having 39 chromosomes most likely received 13 from one diploid parent and 26 chromosomes from the other diploid parent.

Rhododendron 'The Honorable Jean Marie de Montague' is known to throw unreduced gametes and Rhododendron 'Anna' has 'The Honorable Jean Marie de Montague' as a parent.

Summary of Ploidy Levels

Diploid 'Anna',
Diploid 'Loderi Venus',
Diploid 'Norman Gill',
Diploid 'The Honorable Jean Marie de Montague',
Triploid 'Markeeta’s Flame',
Triploid 'Markeeta's Prize'

Source: Greer Gardens

John and Sally Perkins

'Markeeta's Prize' is a Triploid

Rhododendron 'Markeeta's Prize', which is Markeeta Nursery hybrid documented as 'Loderi Venus' x 'Anna', 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 triploid 'Markeeta’s Prize', a diploid crossed with a diploid produced a triploid indicating that unreduced meiosis most likely occurred for one of the diploid parents. In other words, 'Markeeta’s Prize' having 39 chromosomes most likely received 13 from one diploid parent and 26 chromosomes from the other diploid parent.

Rhododendron 'The Honorable Jean Marie de Montague' is known to throw unreduced gametes and Rhododendron 'Anna' has 'The Honorable Jean Marie de Montague' as a parent.

Summary of Ploidy Levels

Diploid 'Anna',
Diploid 'Loderi Venus',
Diploid 'Norman Gill',
Diploid 'The Honorable Jean Marie de Montague',
Triploid 'Markeeta's Flame',
Triploid 'Markeeta's Prize'

Source: Greer Gardens

John and Sally Perkins

'Jean Marie de Montague' is a Diploid

Rhododendron 'The Honourable Jean Marie de Montague', which is a van Nes hybrid documented as R. griffithianum hybrid, has been determined to be a diploid 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 'The Honourable Jean Marie de Montague' is a parent of 'Anita Gehnrich','Grace Seabrook', 'Hallelujah', 'Solidarity', 'Taurus', and 'Very Berry' which are triploids.

Rhododendron 'The Honourable Jean Marie de Montague' appears to produce unreduced gametes in larger numbers than most diploids.

Summary of Ploidy Levels

Diploid 'Anna',
Diploid 'The Honourable Jean Marie de Montague',
Diploid 'Wild Affair',
Triploid 'Anita Gehnrich',
Triploid 'Grace Seabrook',
Triploid 'Hallelujah',
Triploid 'Solidarity',
Triploid 'Taurus',
Triploid 'Very Berry'

Source: Greer Gardens

John and Sally Perkins

'Lem's Monarch' is a Tetraploid

Rhododendron 'Lem's Monarch', which is a Halfdan Lem hybrid documented as 'Anna' x 'Marinus Koster', 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 'Lem's Monarch' has as a descendants 'Rwain'.

In the case of the tetraploid 'Lem's Monarch', a diploid crossed with a tetraploid produced a tetraploid indicating that unreduced meiosis may have occurred for the diploid parent. In other words, 'Lem's Monarch' having 52 chromosomes received something similar to 26 chromosomes from the diploid 'Anna' and 26 chromosomes from the tetraploid 'Marinus Koster'.

Rhododendron 'Lem's Monarch' 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 'El Camino',
Triploid 'Rwain',
Tetraploid 'Lem's Monarch',
Tetraploid 'Marinus Koster',
Tetraploid 'Pink Walloper',
Tetraploid 'Point Defiance',
Tetraploid 'Walloper No. 10'

Source Marc Colombel

John and Sally Perkins

'Taurus' is a Fertile Triploid

Rhododendron 'Taurus', which is a Frank Mossman hybrid documented as 'The Honourable Jean Marie de Montague' x R. strigillosum, 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.

Frank Mossman considered Rhododendron 'Taurus' to be his one standout hybridizing achievement.

Rhododendron 'Taurus', although reluctant to be a parent, appears to be both seed and pollen fertile. Werner Brack raised several seedlings from open pollinated seed collected from a 'Taurus' in his garden. The 'Taurus' in the Brack garden was tested and shown to be a triploid. This provides direct evidence that a triploid Rhododendron can indeed set viable seed.

A seedling of a Jack Rosenthal cross of Rhododendron yakushimanum x 'Taurus' was, also, determined to be a triploid.

In the case of the triploid 'Taurus', a diploid crossed with a diploid produced a triploid indicating that unreduced meiosis most likely occurred for one of the diploid parents. In other words, 'Taurus' having 39 chromosomes most likely received 13 from one diploid parent and 26 chromosomes from the other diploid parent.

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

Rhododendron 'Grace Seabrook', which is also documented as 'The Honorable Jean Marie de Montague' x R. strigillosum, has been determined to be a triploid.

Rhododendron 'The Honorable Jean Marie de Montague', although a diploid, is documented as the parent of several triploids indicating 'The Honorable Jean Marie de Montague' may throw more unreduced gametes than most diploids.

Summary of Ploidy Levels

Diploid 'The Honourable Jean Marie de Montague',
Triploid 'Grace Seabrook',
Triploid 'Taurus',
Triploid A seedling of Rhododendron yakushimanum x 'Taurus'

Source: Greer Gardens
Source: Werner Brack

John and Sally Perkins

'Horizon Monarch' is a Tetraploid

Rhododendron 'Horizon Monarch', which is a Ned Brockenbrough hybrid documented as 'Nancy Evans' x 'Point Defiance', 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 'Horizon Monarch' has as ancestors 'Anna', 'Hotei', 'Lem's Cameo', 'Nancy Evans', 'Norman Gill', 'The Honourable Jean Marie de Montague', 'Horizon Monarch', 'Marinus Koster', and 'Point Defiance'.

In the case of the tetraploid 'Horizon Monarch', a diploid crossed with a tetraploid produced a tetraploid indicating that unreduced meiosis may have occurred for the diploid parent. In other words, 'Horizon Monarch' having 52 chromosomes received something similar to 26 chromosomes from the diploid 'Nancy Evans' and 26 chromosomes from the tetraploid 'Point Defiance'.

Rhododendron 'Horizon Monarch' 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 'Hotei',
Diploid 'Lem's Cameo',
Diploid 'Nancy Evans',
Diploid 'Norman Gill',
Diploid 'The Honourable Jean Marie de Montague',
Triploid 'Steredenn',
Tetraploid 'Horizon Monarch',
Tetraploid 'Marinus Koster',
Tetraploid 'Point Defiance'

Source Marc Colombel

John and Sally Perkins

'Walloper No. 10' is a Tetraploid

Rhododendron 'Walloper No. 10', which is a Halfdan Lem hybrid documented as 'Anna' x 'Marinus Koster', 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 'Walloper No. 10', a diploid crossed with a tetraploid produced a tetraploid indicating that unreduced meiosis may have occurred for the diploid parent. In other words, 'Pink Walloper' having 52 chromosomes received something similar to 26 chromosomes from the diploid 'Anna' and 26 chromosomes from the tetraploid 'Marinus Koster'.

Summary of Ploidy Levels

Diploid 'Anna',
Diploid 'Norman Gill',
Diploid 'The Honourable Jean Marie de Montague',
Triploid 'El Camino',
Tetraploid 'Lem's Monarch',
Tetraploid 'Marinus Koster',
Tetraploid 'Pink Walloper',
Tetraploid 'Point Defiance',
Tetraploid 'Walloper No. 10'

Source: Van Veen Nursery

John and Sally Perkins

'Pink Walloper' is a Tetraploid

Rhododendron 'Pink Walloper', which is a Halfdan Lem hybrid documented as 'Anna' x 'Marinus Koster', 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 'Pink Walloper' has as a descendant 'Super Dog'.

In the case of the tetraploid 'Pink Walloper', a diploid crossed with a tetraploid produced a tetraploid indicating that unreduced meiosis may have occurred for the diploid parent. In other words, 'Pink Walloper' having 52 chromosomes received something similar to 26 chromosomes from the diploid 'Anna' and 26 chromosomes from the tetraploid 'Marinus Koster'.

Summary of Ploidy Levels

Diploid 'Anna',
Diploid 'Norman Gill',
Diploid 'The Honourable Jean Marie de Montague',
Triploid 'El Camino',
Triploid 'Super Dog',
Tetraploid 'Lem's Monarch',
Tetraploid 'Marinus Koster',
Tetraploid 'Pink Walloper',
Tetraploid 'Point Defiance',
Tetraploid 'Walloper No. 10'

John and Sally Perkins

'Point Defiance' is a Tetraploid

Rhododendron 'Point Defiance', which is a Halfdan Lem hybrid documented as 'Anna' x 'Marinus Koster', 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 'Point Defiance' has as descendants 'Doreen Gale', 'Gentle Giant', 'Horizon Monarch', 'Julia Caroline', 'Lady of Spain', 'Orange Leopard', and 'Stony Brook'.

In the case of the tetraploid 'Point Defiance', a diploid crossed with a tetraploid produced a tetraploid indicating that unreduced meiosis may have occurred for the diploid parent. In other words, 'Point Defiance' having 52 chromosomes received something similar to 26 chromosomes from the diploid 'Anna' and 26 chromosomes from the tetraploid 'Marinus Koster'.

Rhododendron 'Point Defiance' 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 'Horizon Lakeside',
Diploid 'Nancy Evans',
Diploid 'Norman Gill',
Diploid 'Orange Leopard',
Diploid 'Stony Brook',
Diploid 'The Honourable Jean Marie de Montague',
Triploid 'El Camino',
Triploid 'Julia Caroline',
Triploid 'Lady of Spain',
Triploid 'Platinum Pearl',
Tetraploid 'Doreen Gale',
Tetraploid 'Gentle Giant',
Tetraploid 'Horizon Monarch',
Tetraploid 'Lem's Monarch',
Tetraploid 'Marinus Koster',
Tetraploid 'Pink Walloper',
Tetraploid 'Point Defiance',
Tetrsploid 'Trude Webster',
Tetraploid 'Walloper No. 10'

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

It is 1913 so What Do You Do?

It is a Beautiful Spring Day in 1913 so What Do You Do?
John and Sally Perkins


Figure 1: Triploids can be Fertile and can create a Bidirectional Pathway Between Ploidy Levels

In spring 1913, George V is the first Windsor King of England, Woodrow Wilson is serving his first term as President of the United States, and World War I is a future event. The 2 most popular Rhododendrons in the world are 'Pink Pearl', a 1890's Waterer hybrid, and 'Cynthia', a 1850's Noble and Standish hybrid. On a beautiful spring day in 1913 if you are Henry 'Harry' White, a nursery manager in Sunningdale, England you cross 'Pink Pearl' by 'Cynthia'. You later name a seedling from this cross 'Countess of Derby'.

In spring 1961, John Kennedy is the young handsome President of the United States and Vietnam is a country unknown to most Americans. On a beautiful spring day in 1961 if you are Harold Greer, living in Eugene, Oregon, you self 'Countess of Derby'. You later name a seedling from this cross 'Trude Webster'.

In spring 1969, Richard Nixon is the President of the United States and Watergate is simply an office building in the DC area. On a beautiful spring day in 1969 if you are Robert Korn in Renton, Washington, you place the pollen from 'Gomer Waterer', a 1900 Waterer 'Pink Pearl' hybrid, onto 'Diane'. You later name a seedling from this cross 'Phyllis Korn'.

In spring 1988, George H. Bush is the Vice President of the United States and Iraq is simply a country somewhere in the Middle East. On a beautiful spring day in 1988 if you are Jim Barlup, living in Bellevue, Washington, you cross 'Whitney's Late Peach' by 'Phyllis Korn'. You later name a seedling from this cross 'Summer Peach'.

In spring 2001, George W. Bush is the President of the United States and the Twin Towers in New York City are still standing. On a beautiful spring day in 2001 if you are Jim Barlup, living in Bellevue, Washington, you cross 'Phyllis Korn' by 'Trude Webster' to create several viable offspring.

So what have you done starting in 1913?

Well you took 2 fertile triploids from the 19th century, namely 'Pink Pearl' and 'Cynthia' and created a tetraploid, namely 'Countess of Derby'. You then selfed the tetraploid 'Countess of Derby' creating a tetraploid, namely 'Truder Webster'. You then placed pollen from the triploid 'Gomer Waterer' onto a diploid seed parent, namely 'Diane' creating a triploid, namely 'Phyllis Korn'. You then used the pollen of a triploid, namely Phyllis Korn' to create a diploid, namely 'Summer Peach'. You then placed the pollen of the tetraploid 'Trude Webster' onto the triploid seed parent 'Phyllis Korn' and produced a series of pentaploid seedlings. See figure 1.

By doing so you ended the myth that triploids are always sterile showing that triploids can be both seed and pollen parents. Moreover, triploids, when used in hybridization, produce both reduced and unreduced gametes. You demonstrated that triploids provide a pathway for the bidirectional transfer of genes between diploids, triploids, tetraploids, and pentaploids.

It took you a few beautiful spring days doing crosses, a few changes of names and addresses, nearly 90 years, and a team of young researchers at the University of Coimbra in Portugal to confirm your results but all in all not a bad piece of work.

Summary of Ploidy Levels

Diploid 'Diane',
Diploid 'Madame Carvalho',
Diploid 'Summer Peach',
Triploid 'Broughtonii',
Triploid 'Cynthia',
Triploid 'Gomer Waterer',
Triploid 'Pink Pearl',
Triploid 'Phyllis Korn',
Tetraploid 'Countess of Derby',
Tetraploid 'Trude Webster', and
Pentaploid Seedlings of 'Phyllis Korn' X 'Trude Webster'

Flow cytometry to determine ploidy levels performed 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 following people and organizations donored samples for this reasearch:

John Abbott,
Vivian Abney of East Fork Nursery,
Arnold Arboretum,
Audra State Park, WV,
Jim Barlup,
Barlett Arboretum,
Jane Brooks,
Joe Bruso,
Canobie Lake, NH,
Dick Cavender,
Werner Brack,
Ned Brockenbrough,
Marc Colombel,
Bruce Clyburn,
Connecticut College Arboretum,
Mike Creel,
Al Fitzburg,
Robert Fox,
Harold Greer of Greer Gardens,
George Hibben,
Highstead Arboretum,
Don Hyatt,
Lindy Johnson of Appalachian Native Plants,
Richard Jaynes of Broken Arrow Nursery,
Doug Jolley,
Fred Knippel,
Longwood Gardens,
Ron Miller,
Dick Murcott,
John and Sally Perkins,
Planeview Nursery,
Ron Rabideau of RareFind Nursery,
Ellie Sather of Whitney Gardens,
Stoddard Blog, NH,
John Thornton,
Hendrik Van Oostand of Azaleatuin,
Kathy Van Veen of Van Veen Nursery

'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

'Val d'Aulnay' is a Fertile Triploid

Rhododendron 'Val d'Aulnay', which is a Croux and Fils hybrid, 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.

Rhododendron 'Val d'Aulnay' is the seed parent of 'L'Engin', which has been determined to be tetraploid. 'Lem's Cameo', which has been determined to be diploid, is the pollen parent of 'L'Engin'.

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 'Lem's Cameo',
Triploid 'Val d'Aulnay',
Tetraploid L'Engin

Source Marc Colombel

John and Sally Perkins

'Very Berry' is a Tetraploid

Rhododendron 'Very Berry', which is a Harold Greer hybrid documented as 'Trude Webster' x 'The Honorable Jean Marie de Montague', 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.

'Very Berry' has 'Broughtonii', 'Pink Pearl', 'Cynthia', 'Countess of Derby', 'Trude Webster', and 'The Honorable Jean Marie de Montague' as ancestors. 'Verry Berry' appears to be another case where 'The Honorable Jean Marie de Montague' threw unreduced gametes.

Summary of Ploidy Levels

Diploid 'The Honorable Jean Marie de Montague',
Triploid 'Broughtonii',
Triploid 'Cynthia',
Triploid 'Pink Pearl',
Tetraploid 'Countess of Derby',
Tetraploid 'Trude Webster',
Tetraploid 'Very Berry'

Source: Greer Gardens

John and Sally Perkins

'Nancy Evans' is a Diploid

Rhododendron 'Nancy Evans', which is a Ned Brockenbrough hybrid documented as 'Hotei' x 'Lem's Cameo', has been determined to be a diploid 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.

This Coimbra based research team also determined that 'Hotei' and 'Lem's Cameo' are diploids.

Rhododendron 'Nancy Evans' is seed fertile but pollen sterile.

'Nancy Evans' is the seed parent of 'Horizon Monarch', which was determined to be a tetraploid using flow cytometry by Dr. Thomas Ranney, J.R. Jones, and Nathan Lynch. This indicates that 'Nancy Evans' may occasionally throw unreduced gametes.

Summary of Ploidy Levels

Diploid 'Hotei',
Diploid 'Lem's Cameo',
Diploid 'Nancy Evans',
Tetraploid 'Horizon Monarch'

Source: Whitney Nursery

John and Sally Perkins

'Anita Gehnrich' is a Triploid

Rhododendron 'Anita Gehnrich', which is a Bud Gehnrich hybrid documented as 'The Honorable Jean Marie de Montague' X R. degronianum ssp. yakushimanum, 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.

Rhododendron 'The Honorable Jean Marie de Montague', although a diploid, is documented as the parent of several triploids indicating 'The Honorable Jean Marie de Montague' may throw more unreduced gametes than most diploids.

Rhododendron 'Solidarity', which is documented as having the reversed parents of 'Anita Gehnrich', is also a triploid.

Summary of Ploidy levels

Diploid 'The Honorable Jean Marie de Montague',
Triploid 'Anita Gehnrich',
Triploid 'Solidarity'

Source: Werner Brack

John and Sally Perkins