tridentata chromosome followup

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Dear Vic: et al.

            I promised I would give you the full citation for the count of 40 chromosomes for Iris tridentata. It is ?Chromosome Cytology of Iridaceae?Patterns of Variation, Determination of Ancestral Base Numbers, and Modes of Karyotype Change.? By Peter Goldblatt and Masahiro Takei in Annals of the Missouri Botanical Garden, Vol 84, pages 285-304, 1997.

            The article covers the entire family but Iris tridentata is the only species in the Genus Iris listed. The article proposes that the base number x=10 is ancestral for the tribe Irideae within the family. Since most of the discussion centers around Moraea they note that dysploid reduction in at least four lineages of Moraea has resulted in the independent evolution of the secondary base of x=6. Although the genus Iris is not discussed one might assume a similar secondary evolutionary origin of bases x=8 and x=12. That reasoning would put the beardless with 2n=40 as ancestral and the bearded with separate lineages with 2n=16 and 24. Since this is an extrapolation without any real data connected, one should be guarded in accepting my remarks.