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
