Rhododendron columbianum is a Diploid

Rhododendron columbianum has been determined to be a diploid 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 columbianum is often documented as being a hybrid between Rhododendron groenlandicum and Rhododendron neoglandulosum. Since Rhododendron groenlandicum and Rhododendron neoglandulosum are tetraploid, Rhododendron columbianum, being diploid, is most likely a separate species.

Summary of Ploidy Levels

Diploid Rhododendron columbianum,
Diploid Rhododendron subarticum,
Diploid Rhododendron subulatum China,
Tetraploid Rhododendron diversipilosum,
Tetraploid Rhododendron diversipilosum 'Milky Way',
Tetraploid Rhododendron groenlandicum,
Tetraploid Rhododendron groenlandicum Saco Bog, Maine,
Tetraploid Rhododendron hypoleucum,
Tetraploid Rhododendron neoglandulosum,
Tetraploid Rhododendron tolmachevii,
Tetraploid Rhododendron tomentosum Turku Archipelago

Source: Kristian Theqvist
Source: Hans Eiberg
Source: Robert MacIntyre

John and Sally Perkins

Rhododendron tolmachevii is a Tetraploid

Rhododendron tolmachevii 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

Summary of Ploidy Levels

Diploid Rhododendron columbianum,
Diploid Rhododendron subarticum,
Diploid Rhododendron subulatum China,
Tetraploid Rhododendron diversipilosum,
Tetraploid Rhododendron diversipilosum 'Milky Way',
Tetraploid Rhododendron groenlandicum,
Tetraploid Rhododendron groenlandicum Saco Bog, Maine,
Tetraploid Rhododendron hypoleucum,
Tetraploid Rhododendron neoglandulosum,
Tetraploid Rhododendron tolmachevii,
Tetraploid Rhododendron tomentosum Turku Archipelago

Source: Kristian Theqvist
Source: John and Sally Perkins

John and Sally Perkins

Rhododendron neoglandulosum is a Tetraploid

Rhododendron neoglandulosum 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

Summary of Ploidy Levels

Diploid Rhododendron columbianum,
Diploid Rhododendron subarticum,
Diploid Rhododendron subulatum China,
Tetraploid Rhododendron diversipilosum,
Tetraploid Rhododendron diversipilosum 'Milky Way',
Tetraploid Rhododendron groenlandicum,
Tetraploid Rhododendron groenlandicum Saco Bog, Maine,
Tetraploid Rhododendron hypoleucum,
Tetraploid Rhododendron neoglandulosum,
Tetraploid Rhododendron tolmachevii,
Tetraploid Rhododendron tomentosum Turku Archipelago

Source: Kristian Theqvist

John and Sally Perkins

Rhododendron hypoleucum is a Tetraploid

Rhododendron hypoleucum 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

Summary of Ploidy Levels

Diploid Rhododendron columbianum,
Diploid Rhododendron subarticum,
Diploid Rhododendron subulatum China,
Tetraploid Rhododendron diversipilosum,
Tetraploid Rhododendron diversipilosum 'Milky Way',
Tetraploid Rhododendron groenlandicum,
Tetraploid Rhododendron groenlandicum Saco Bog, Maine,
Tetraploid Rhododendron hypoleucum,
Tetraploid Rhododendron neoglandulosum,
Tetraploid Rhododendron tolmachevii,
Tetraploid Rhododendron tomentosum Turku Archipelago

Source: Kristian Theqvist

John and Sally Perkins

Rhododendron diversipilosum is a Tetraploid

Rhododendron diversipilosum 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 diversipilosum was formerly classified as Ledum palustre var. diversipilosum.

Summary of Ploidy Levels

Diploid Rhododendron columbianum,
Diploid Rhododendron subarticum,
Diploid Rhododendron subulatum China,
Tetraploid Rhododendron diversipilosum,
Tetraploid Rhododendron diversipilosum 'Milky Way',
Tetraploid Rhododendron groenlandicum,
Tetraploid Rhododendron groenlandicum Saco Bog, Maine,
Tetraploid Rhododendron hypoleucum,
Tetraploid Rhododendron neoglandulosum,
Tetraploid Rhododendron tolmachevii,
Tetraploid Rhododendron tomentosum Turku Archipelago

Source: Kristian Theqvist

John and Sally Perkins

Rhododendron groenlandicum Saco Bog is a Tetraploid

Rhododendron groenlandicum Saco Bog 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 groenlandicum was formerly classified as Ledum groenlandicum.

Summary of Ploidy Levels

Diploid Rhododendron columbianum,
Diploid Rhododendron subarticum,
Diploid Rhododendron subulatum China,
Tetraploid Rhododendron diversipilosum,
Tetraploid Rhododendron diversipilosum 'Milky Way',
Tetraploid Rhododendron groenlandicum,
Tetraploid Rhododendron groenlandicum Saco Bog, Maine,
Tetraploid Rhododendron hypoleucum,
Tetraploid Rhododendron neoglandulosum,
Tetraploid Rhododendron tolmachevii,
Tetraploid Rhododendron tomentosum Turku Archipelago

Source: Saco Bog, Maine (John and Sally Perkins)

John and Sally Perkins

Rhododendron tomentosum Turku Archipelago is a Tetraploid

Rhododendron tomentosum Turku Archipelago 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 tomentosum was formerly classified as Ledum.

Summary of Ploidy Levels

Diploid Rhododendron columbianum,
Diploid Rhododendron subarticum,
Diploid Rhododendron subulatum China,
Tetraploid Rhododendron diversipilosum,
Tetraploid Rhododendron diversipilosum 'Milky Way',
Tetraploid Rhododendron groenlandicum,
Tetraploid Rhododendron groenlandicum Saco Bog, Maine,
Tetraploid Rhododendron hypoleucum,
Tetraploid Rhododendron neoglandulosum,
Tetraploid Rhododendron tolmachevii,
Tetraploid Rhododendron tomentosum Turku Archipelago

Source: Kristian Theqvist

John and Sally Perkins

Rhododendron mucronulatum 'Waka Mirasaki' is a Diploid

Rhododendron mucronulatum 'Waka Mirasaki' 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 mucronulatum,
Diploid Rhododendron mucronulatum 'Waka Mirasaki'

Source: John and Sally Perkins

John and Sally Perkins

Rhododendron minus 'Blanchette' is a Diploid

Rhododendron minus 'Blanchette' 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.

No naturally occurring tetraploid Rhododendron minus have been located to date. Rhododendron minus 'Epoch', which was chemically treated to increase the ploidy level, is a tetraploid.

Summary of Ploidy Levels

Diploid Rhododendron minus,
Diploid Rhododendron minus 'Blanchette',
Diploid Rhododendron minus 'Mitchell Dam',
Diploid Rhododendron minus var. chapmanii,
Tetraploid 'Epoch'

Source: John and Sally Perkins

John and Sally Perkins

Rhododendron minus var. chapmanii is a Diploid

Rhododendron minus var. chapmanii 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.

No naturally occurring tetraploid Rhododendron minus have been located to date. Rhododendron minus 'Epoch', which was chemically treated to increase the ploidy level, is a tetraploid.

Summary of Ploidy Levels

Diploid Rhododendron minus,
Diploid Rhododendron minus 'Blanchette',
Diploid Rhododendron minus 'Mitchell Dam',
Diploid Rhododendron minus var. chapmanii,
Tetraploid 'Epoch'

Source: Ron Miller

John and Sally Perkins

Rhododendron hippophaeoides 'Silver Blue' is a Diploid

Rhododendron hippophaeoides 'Silver Blue' has been determined to be a diploid 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

Diploid Rhododendron hippophaeoides 'Silver Blue'

Source: RareFind Nursery

John and Sally Perkins

Rhododendron groenlandicum is a Tetraploid

Rhododendron groenlandicum 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 groenlandicum was formerly classified as Ledum groenlandicum.

Summary of Ploidy Levels

Diploid Rhododendron columbianum,
Diploid Rhododendron subarticum,
Diploid Rhododendron subulatum China,
Tetraploid Rhododendron diversipilosum,
Tetraploid Rhododendron diversipilosum 'Milky Way',
Tetraploid Rhododendron groenlandicum,
Tetraploid Rhododendron groenlandicum Saco Bog, Maine,
Tetraploid Rhododendron hypoleucum,
Tetraploid Rhododendron neoglandulosum,
Tetraploid Rhododendron tolmachevii,
Tetraploid Rhododendron tomentosum Turku Archipelago

Source: Bartlett Arboretum
Source: Saco Bog, Maine (John and Sally Perkins)
Source: Kristian Theqvist

John and Sally Perkins

Rhododendron augustinii Berg is a Tetraploid

Rhododendron augustinii Berg 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 augustinii Berg form

Source: RareFind Nursery

John and Sally Perkins

Rhododendron diversipilosum 'Milky Way' is a Tetraploid

Rhododendron diversipilosum 'Milky Way' 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 diversipilosum was formerly classified as Ledum palustre var. diversipilosum.

Summary of Ploidy Levels

Diploid Rhododendron columbianum,
Diploid Rhododendron subarticum,
Diploid Rhododendron subulatum China,
Tetraploid Rhododendron diversipilosum,
Tetraploid Rhododendron diversipilosum 'Milky Way',
Tetraploid Rhododendron groenlandicum,
Tetraploid Rhododendron groenlandicum Saco Bog, Maine,
Tetraploid Rhododendron hypoleucum,
Tetraploid Rhododendron neoglandulosum,
Tetraploid Rhododendron tolmachevii,
Tetraploid Rhododendron tomentosum Turku Archipelago

Source: RareFind Nursery
Source: Kristian Theqvist

John and Sally Perkins

Rhododendron minus 'Mitchell Dam' is a Diploid

Rhododendron minus 'Mitchell Dam', which has large leaves and stems and has been suspected of being a tetraploid, 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.

No naturally occurring tetraploid Rhododendron minus have been located to date. Rhododendron minus 'Epoch', which was chemically treated to increase the ploidy level, is a tetraploid.

Summary of Ploidy Levels

Diploid Rhododendron minus,
Diploid Rhododendron minus 'Blanchette',
Diploid Rhododendron minus 'Mitchell Dam',
Diploid Rhododendron minus var. chapmanii,
Tetraploid 'Epoch'

Source: John Thornton

John and Sally Perkins

Rhododendron subulatum China is a Diploid

5 plants of Rhododendron subulatum from China growing at the Arnold Arboretum 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 subulatum was formerly classified as subspecies of Ledum palustre.

The 5 plants of Rhododendron subulatum tested as diploid were from northern China.

A Rhododendron tomentosum wild collected from a marsh in Turku Archipelago, Finland tested as tetraploid.

There is a very good chance that this difference in ploidy level is due to misidentification of the plant from China due to the large group of plants formerly included under Ledum palustre and then compounded when the Ledum genus was moved to Rhododendron.

The plant from China is clearly a diploid "Ledum". The origin of the plant tested is well documented. This plant is still growing at the Arnold Arboretum along with 4 of its siblings.

Summary of Ploidy Levels

Diploid Rhododendron columbianum,
Diploid Rhododendron subarticum,
Diploid 5 plants of Rhododendron subulatum China,
Tetraploid Rhododendron diversipilosum,
Tetraploid Rhododendron diversipilosum 'Milky Way',
Tetraploid Rhododendron groenlandicum,
Tetraploid Rhododendron groenlandicum Saco Bog, Maine,
Tetraploid Rhododendron hypoleucum,
Tetraploid Rhododendron neoglandulosum,
Tetraploid Rhododendron tolmachevii,
Tetraploid Rhododendron tomentosum Turku Archipelago

Source: Arnold Arboretum Accession Number: Ledum palustre 389-97-A,B,C,D,E Wild collected in China

John and Sally Perkins

Rhododendron racemosum is a Diploid

Rhododendron racemosum 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 racemosum

Source: John and Sally Perkins

John and Sally Perkins

Rhododendron keiskei is a Diploid

Rhododendron keiskei 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 keiskei

Source: John and Sally Perkins

John and Sally Perkins

Rhododendron mucronulatum is a Diploid

Rhododendron mucronulatum 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 mucronulatum,
Diploid Rhododendron mucronulatum 'Waka Mirasaki'

Source: Arnold Arboretum Accession Number: 968-85

John and Sally Perkins

Rhododendron dauricum 'Delp's Dwarf' is a Diploid

Rhododendron dauricum 'Delp's Dwarf' 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 dauricum 'Delp's Dwarf'

Source: Joe Bruso

John and Sally Perkins