Re: tetraploid
From: Vicki Craig <craigiris@earthlink.net>
Hi,
Sharon has done a wonderful explanation of tetraploids but I would like
to add some things. Pumila, the small iris which were crossed with the
tall bearded iris to produce standard dwarf bearded iris have two sets
of 8 chromosomes or 8-8-8-8. That makes pumila a tetraploid. Modern tall
bearded (those big beautiful things one sees in most all TB catalogs)are
also tetraploids having 2 sets of 12 chromosomes. i.e. 12-12-12-12. when
these two tetraploids are crossed they can produce an iris which has two
sets of chromosomes 8-8-12-12. These are not tetraploids. they are
called an amphi-diploid. Somehow the mistaken notion of if you cross
two tetraploids of any count the results will be another tetraploid. Not
true.
Hope this helps clear this subject up. And yes even hybridizers who are
unfamiliar with the genetic make-up of different iris can err in their
terminology. Based on the background of Blue Chip Stock and without a
chromosome count I would place my money on it not being a tetraploid.
Vicki
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