I think too that in general plants in the north tend to have more polyploids Saying so one compares genera not individual species. This may have to do with the fact that in warmer climates there is more compitition for fast grow and any surplus DNA is a burden then On the contrary in the north plants often divide their time in a period with increasing celle numbers and a period with increae in size of these cells. Most big narcissi, tulips Hippeastrums are tetraploids I suppose they were not only chosen for the increased flower size but also for increases in hardiness, This latter not compared to other species but compared with their diploid parent. Ben J.M.Zonneveld Institute of Biology,Leiden University, Clusius lab Wassenaarse weg 64, 2333 AL Leiden, The Netherlands Zonneveld@rulbim.Leidenuniv.NL Fax: +31-71-5274999. min temp -10C (15F)