Rhododendron 'Altaclerensis', which is a 1862 Lee exhibited F.C.C Ghent hybrid documented as Rhododendron molle x unknown Ghent hybrid, 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 Rhododendron 'Altaclerensis' tested here is the yellow flowered one which is different from the 1842 'Altaclarense' introduced by Lord Carvanon in Highclere.
History of the earlier 'Altaclarense':
Azalea altaclarensis - Gowen apud Lindley in Bot. Reg. XXVIII. t. 27 (1842),
not Rhododendron altaclarense Lindl.
This handsome hybrid was raised at Highclere by J. R. Gowen, who states
that "it was produced by fertilizing the flowers of Azalea sinensis with the pollen
of the late flowering variety of Azalea viscosa, called by nurserymen A. rubescens
major." The flowers are large white, slightly bordered pink, with a faint yellow
tinge at the base of the lobes, and with the upper lobe distinctly dotted yellow
and the tube pinkish outside. The gradually dilated tube and the yellow tinge
and the spotted upper lobe indicate the influence of R. sinense and the white
color and hirsute tube of the corolla and the delicious fragrance the influence of
R. viscosum.
Summary of Ploidy Levels
Diploid Rhododendron molle,
Triploid 'Aida',
Triploid 'Bronze Unique',
Triploid 'Daviesii',
Triploid 'Deep Rose',
Triploid 'Gloria Mundi',
Triploid 'Josephine Klinger',
Tetraploid 'Admiraal De Ruyter',
Tetraploid 'Altaclerensis',
Tetraploid 'Ariel',
Tetraploid 'Beaté Céleste',
Tetraploid 'Bijou des Amateurs',
Tetraploid' Bouquet de Flore',
Tetraploid 'Comte de Flandre',
Tetraploid 'Heureuse Surprise',
Tetraploid 'Ignacea',
Tetraploid 'Julius Caesar',
Tetraploid 'Lelia',
Tetraploid 'Madame Gustave Guillemot',
Tetraploid 'Nancy Waterer',
Tetraploid 'Oscar I',
Tetraploid 'Raphael de Smet'
Source: Azaleatuin
John and Sally Perkins
