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Rhododendron columbianum R. comisteum Til B R. collettianum

Rhododendron columbianum, 2N

 R. columbianum. Foto: Hans Eiberg
R. columbianum. Foto: Hans Eiberg

 R. columbianum. Foto: Hans Eiberg
R. columbianum. Foto: Hans Eiberg

 R. columbianum. Foto: Hans Eiberg
Rhododendron columbianum, cw Lincoln Beach Oregon Rich Craven, USA, ARS 71 2004. Foto: Hans Eiberg

Blomst, R. columbianum K. Thekvist


R. columbianum (Ledum) har været betragtet som en hybrid af R. groenlandicum × R. neoglandulosum, men begge er tetraploide. men nye undersøgelser af den viste plante, viser at denne er diploid** (by Dr. João Loureiro, University of Coimbra in Portugal i samarbejde med J. Perkins mm.). Frøholdet fra ARS 71/2004 viste ringe spredning. Alle var smalbladet med ringe indument. Vinteren i Danmark er hård ved planten. men den kommer sig pænt, så i juni-juli ses skaderne ikke. Vokser vildt i Oregon, USA. H.Eiberg
**The collection of samples from the Ledum species was coordinated by John Perkins, American Rhododendron Society, Chapter 6, Salem, New Hampshire, USA. In the tests R. groenlandicum and R. neoglandulosum were found to be tetraploids and R. ×columbianum was found to be a diploid (Samples of R. columbianum, m.m. were from Hans Eiberg). This means that R. ×columbianum cannot be a cross of the two Ledum species. It is a true species, not a cross, and should accordingly be called R. columbianum without the multiplication sign ×.(João Loureiro, J. Perkins et al. (and H. Eiberg and K. Thekvist)).
Link to the poster on Ploidy level estimations in decidious and elepidote hybrids of Rhododendron.
Link to the results of tested ploidy levels of Ledum species:

Flora of North America
D. Genbank Incl. sammen med Ledum neoglandulosum i R. columbianum Burke Museum