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RE: Sam Norris; Christy's seedlings


Sam Norris has also done a lot of work on arils and arilbreds, growing both
in the difficult conditions for them found in Kentucky.  I grew some of his
material years ago, obtaining it through the ASI plant sale.  Some of the
seedlings looked very aril, but were decent growers here.  One or two are
still surviviing (I think) after more than 15 years of neglect.  After
repeated generations, Sam had bred out most of the TB appearance of the
blooms but managed to keep some of the plant vigor.

I have some seedlings (about 20) of the 4N Pardancandas, but suspect I will
have to wait until next year to see bloom.  They have been rather slow for
me.

Now as for the JI/Sib hybrids reported by Christy Hensler:  There are
reasons for skepticism.  Originally, the cross was reported as having been
made BOTH ways, now as JI X Sib only.  Under the original reports, it was
believable to suspect that in both cases, self-pollination took place,
because the seedlings either appear to be pure JI or pure Siberian.  Now if
it was JI X Sib only, it becomes very difficult to explain, by any
principles of genetics known to me, how the JI genes and the Siberian genes
perfectly segregate to produce only offspring that look like one or the
other, but none with intermediate characteristics.  A survey of wide-cross
progeny in the history of iris breeding shows that the F1 generation is
almost always a mix of the characteristics of both parents.  I know of no
previous case in iris breeding or in other plant breeding where both
parental phenotypes segregated out perfectly in the F1.  If there are such
cases, I would be happy to be enlightened.

The evident easy fertility of both the original cross, repeated several
times, and the offspring with the parents and among themselves, also does
not fit what we know of plant genetics.  Even when two relatively close
iris types are crossed (Aril x bearded; siberica x setosa; siberica x PCI,
pseudacorus x JI), the progeny are either sterile or have only very limited
fertility.  Wouldn't you reasonably expect that from types as divergent as
JI and Siberian, which have never been crossed before in the history of
iris breeding, the progeny would be sterile or almost so?

So, there are reasons for keeping an open mind with regard to this cross.
The chromosome counts (at least one of them) suggest intermediacy, but
cytogeneticists routinely repeat such counts many times.  Was Sam's count
from one cell or did he survey several cells and root tips (assuming the
count was made using root tip cells)?  The 26-chromosome plant should
certainly be sterile or have limited fertility with either parent, because
it would produce 13-chromosome gametes, and in crosses with either parent
there would be a univalent (unpaired chromosome).

I was dismayed at the quotes from "The Experts Speak," a mischievious
little book that suggests that "experts" are usually wrong, because, for
example, Lord Kelvin was far off about the age of the Earth.  Kelvin was
perfectly justified in proposing a young age for the Earth (and thus the
difficulties for the theory of natural selection) based on the data he had
at hand.  He based his estimate on the rate of cooling of the planet from
an original molten state, but because he worked and wrote before the
discovery of radioactive decay, was not able to factor in this source of
continued heat.

Why are the "experts" experts?  Because they're usually right.  Simply
because they are not 100% right is no reason to discard their views.
Clarence Mahan is as knowledgeable about irises as anyone living, and his
views, based on sound reasoning, deserve more than this sort of flippant
treatment.

Science is based on skepticism.  New ideas, theories and discoveries face a
stiff uphill climb, and that is as it should be.  Thorough testing of new
material assures that it will be either justifiably rejected, or integrated
into our world view.  Scientists also agree that the more extraordinary the
claims, the more extraordinary the evidence must be.  This seems like just
such a case.

So, like Clarence, I am not inclined at this time to accept the
interspecies nature of the Hensler seedlings.  When the original crosses
are repeated by a second hybridizer or even a third or fourth, under
rigorously controlled conditions, and repeated chromosome counts or
intermediate appearance and limited fertility confirm the results, I'll be
happy to switch.


Bill Shear
Department of Biology
Hampden-Sydney College
Hampden-Sydney VA 23943
(804)223-6172
FAX (804)223-6374
email<wshear@email.hsc.edu>
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