Rhododendron luteum Yellow form is a Tetraploid

Rhododendron luteum Yellow form has been determined to be a tetraploid using flow cytometry by

Dr. João Loureiro, Dr. Silvia Castro, 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 luteum was also determined to be a tetraploid using flow cytometry by Dr. Thomas Ranney, J.R. Jones, and Nathan Lynch.

Summary of Ploidy Levels

Tetraploid Rhododendron luteum,
Tetraploid Rhododendron luteum 'Golden Comet',
Tetraploid Rhododendron luteum Orange form,
Tetraploid Rhododendron luteum Yellow form

Source: Kristian Theqvist

John and Sally Perkins

Rhododendron luteum Orange form is a Tetraploid

Rhododendron luteum Orange form has been determined to be a tetraploid using flow cytometry by

Dr. João Loureiro, Dr. Silvia Castro, 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 luteum was also determined to be a tetraploid using flow cytometry by Dr. Thomas Ranney, J.R. Jones, and Nathan Lynch.

Summary of Ploidy Levels

Tetraploid Rhododendron luteum,
Tetraploid Rhododendron luteum 'Golden Comet',
Tetraploid Rhododendron luteum Orange form,
Tetraploid Rhododendron luteum Yellow form

Source: Kristian Theqvist

John and Sally Perkins

Rhododendron "alabamense not" is a Tetraploid

A plant labeled Rhododendron alabamense 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.

The ploidy test indicates this plant may instead be Rhododendron colemanii.

Summary of Ploidy Levels

Diploid Rhododendron alabamense,
Tetraploid Rhododendron colemanii,
Tetraploid Rhododendron "alabamense not"

Source: Rarefind Nursery

John and Sally Perkins

Rhododendron luteum is a Tetraploid

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

Summary of Ploidy Levels

Tetraploid Rhododendron luteum,
Tetraploid Rhododendron luteum 'Golden Comet',
Tetraploid Rhododendron luteum Orange form,
Tetraploid Rhododendron luteum Yellow form

Source: Arnold Arboretum
Source: John and Sally Perkins
Source: Kristian Theqvist

John and Sally Perkins

Rhododendron viscosum forma rhodanthum is a Diploid

Rhododendron viscosum forma rhodanthum 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 viscosum forma rhodanthum appears to be a natural hybrid most likely containing Rhododendron cumberlandense.

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

Summary of Ploidy Levels

Diploid Rhododendron cumberlandense,
Diploid Rhododendron viscosum,
Diploid Rhododendron viscosum forma rhodanthum,
Diploid Rhododendron viscosum var. serrulatum

Source: Arnold Arboretum Accession Number: 638-62

John and Sally Perkins

Rhododendron viscosum var. serrulatum is a Diploid

Rhododendron viscosum var. serrulatum 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 viscosum was also determined to be a diploid using flow cytometry by Dr. Thomas Ranney, J.R. Jones, and Nathan Lynch.

Summary of Ploidy Levels

Diploid Rhododendron viscosum,
Diploid Rhododendron viscosum forma rhodanthum,
Diploid Rhododendron viscosum var. serrulatum

Source: Connecticut College Arboretum Accession Number: 90-7-A

John and Sally Perkins

Rhododendron calendulaceum var. croceum is a Tetraploid

Rhododendron calendulaceum var. croceum 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 calendulaceum was also determined to be a tetraploid using flow cytometry by Dr. Thomas Ranney, J.R. Jones, and Nathan Lynch.

Summary of Ploidy Levels

Tetraploid Rhododendron calendulaceum,
Tetraploid Rhododendron calendulaceum var. croceum,
Tetraploid Rhododendron calendulaceum 'Cherokee',
Tetraploid Rhododendron calendulaceum 'Smoky Mountaineer'

Source: Arnold Arboretum Accession Number: 17758-1-A

John and Sally Perkins

Rhododendron austrinum Album Form is a Tetraploid

Rhododendron austrinum Album Form 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.

Summary of Ploidy Levels

Tetraploid Rhododendron austrinum,
Tetraploid Rhododendron austrinum Album Form,
Tetraploid Rhododendron austrinum 'Millie Mac'

Source: Mike Creel

John and Sally Perkins

Rhododendron atlanticum 'Winterthur' is a Tetraploid

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

Summary of Ploidy Levels

Tetraploid Rhododendron atlanticum,
Tetraploid Rhododendron atlanticum 'Winterthur'

Source: Woodlanders

John and Sally Perkins

Rhododendron arborescens Pink Form is a Diploid

Rhododendron arborescens Pink Form 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 arborescens was also determined to be a diploid using flow cytometry by Dr. Thomas Ranney, J.R. Jones, and Nathan Lynch.

Summary of Ploidy Levels

Diploid Rhododendron arborescens,
Diploid Rhododendron arborescens Pink Form,
Diploid Rhododendron arborescens Yellow Form Gable

Source: George Hibben

John and Sally Perkins

Rhododendron periclymenoides 'Appalachian Spring' is a Diploid

Rhododendron periclymenoides 'Appalachian Spring' 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 periclymenoides was also determined to be a diploid using flow cytometry by Dr. Thomas Ranney, J.R. Jones, and Nathan Lynch.

Summary of Ploidy Levels

Diploid Rhododendron periclymenoides,
Diploid Rhododendron periclymenoides 'Appalachian Spring',
Diploid Rhododendron periclymenoides 'Doug Horegan'

Source: John and Sally Perkins

John and Sally Perkins

Rhododendron prunifolium is a Diploid

Rhododendron prunifolium 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.

Summary of Ploidy Levels

Diploid Rhododendron prunifolium,
Diploid Rhododendron prunifolium 'David Ellis'

Source: Arnold Arboretum Accession Number: 85-D
Source: Connecticut College Arboretum Accession Number: 83-39-A

John and Sally Perkins

Rhododendron alabamense is a Diploid

Rhododendron alabamense 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.

Summary of Ploidy Levels

Diploid Rhododendron alabamense,
Diploid Rhododendron alabamense 'Schwinds'

Source: Connecticut College Arboretum Accession Number: 81-84-A
Source: Connecticut College Arboretum Accession Number: 85-2-A
Source: Connecticut College Arboretum Accession Number: 85-2-C
Source: Highstead Arboretum Accession Number: 94-6-L
Source: Woodlanders

John and Sally Perkins

Rhododendron flammeum is a Diploid

Rhododendron flammeum 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.

Summary of Ploidy Levels

Diploid Rhododendron flammeun,
Diploid Rhododendron flammeum 'Brick Ruffles',
Diploid Rhododendron flammeum 'Harry's Speciosum',
Diploid Rhododendron flammeum 'Hazel Hamilton'

Source: Connecticut College Arboretum Accession Number: 85-3-B

John and Sally Perkins

Rhododendron calendulaceum 'Smoky Mountaineer' is a Tetraploid

Rhododendron calendulaceum 'Smoky Mountaineer' 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

Tetraploid Rhododendron calendulaceum,
Tetraploid Rhododendron calendulaceum var. croceum,
Tetraploid Rhododendron calendulaceum 'Cherokee',
Tetraploid Rhododendron calendulaceum 'Smoky Mountaineer'

Source: Arnold Arboretum Accession Number: 22690

John and Sally Perkins

Rhododendron arborescens Yellow Form Gable is a Diploid

Rhododendron arborescens Yellow Form Gable 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 arborescens was also determined to be a diploid using flow cytometry by Dr. Thomas Ranney, J.R. Jones, and Nathan Lynch.

Summary of Ploidy Levels

Diploid Rhododendron arborescens,
Diploid Rhododendron arborescens Pink Form,
Diploid Rhododendron arborescens Yellow Form Gable

Source: John and Sally Perkins

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

"Miller's pink austrinum" is a Tetraploid

Rhododendron "pink austrinum" 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.

According to Ron Miller, Rhododendron "pink austrinum" exists as populations containing no yellow Rhododendron austrinum on the Yellow River in Florida. No decision has been made to whether this is a species separate from Rhododendron austrinum, a subspecies of Rhododendron austrinum, or a merely a pink form or variety of Rhododendron austrinum. Populations containing both pink tetraploids and yellow tetraploids resembling Rhododendron austrinum also exist. These tetraploid populations are not colocated with any diploid populations that bloom at the time the tetraploids are in bloom. There are no triploids in these populations.

Rhododendron "pink austrinum" was also determined to be a tetraploid using flow cytometry by Dr. Thomas Ranney, J.R. Jones, and Nathan Lynch.

Summary of Ploidy Levels

Tetraploid Rhododendron atlanticum,
Tetraploid Rhododendron austrinum,
Tetraploid Rhododendron calendulcaeum,
Tetraploid Rhododendron colemanii,
Tetraploid Rhododendron luteum,
Tetraploid Rhododendron "pink austrinum"

Source: Ron Miller

John and Sally Perkins

"Coleman's May Pink" is a Tetraploid

Rhododendron colemanii "Coleman's May Pink" 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.

Summary of Ploidy Levels

Tetraploid Rhododendron colemanii,
Tetraploid Rhododendron colemanii "Coleman's May Pink"

Source: Connecticut College Arboretum

John and Sally Perkins

Rhododendron colemanii is a Tetraploid

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

Summary of Ploidy Levels

Tetraploid Rhododendron atlanticum,
Tetraploid Rhododendron austrinum,
Tetraploid Rhododendron calendulcaeum,
Tetraploid Rhododendron colemanii,
Tetraploid Rhododendron colemanii "Coleman's May Pink",
Tetraploid Rhododendron luteum,
Tetraploid Rhododendron "pink austrinum"

Source: John Thornton

John and Sally Perkins