Re: OT: Chimera
I found Dave's going back into early mythological uses of the word "chimera"
interesting, and not at all irrelevant. In each case the creature (of the
imagination) was made up of disparate parts and pieces from various natural
beasts and were meant to display the qualities those various creatures had.
Our genetic or phenological use of the word derives directly from the use of
the word for those mythological beasts.
Dave's mention of some chimeras that result from grafting is both accurate and
interesting. The tissues right at the graft line sometimes produce apical
meristems (terminals from which shoots develop) that include segments of
tissues from both the rootstock and the scion (ingrafted top part). I think
some have used the word "graft hybrid" for these, but that confuses the
meaning of "hybrid." The questions I've been asked about how new iris
varieties are produced often assume grafting is involved. Why sexual
propagation should seem strange in plants is beyond me, especially as I have
never seen a child who has not picked a dandylion seed head and puffed the
individual seeds into the air. Somehow many folks just do not make the
Grafts, incidentally, usually require closely related stock, but some grafts
have been made between very wide evolutionary separates--including, I believe,
in a case or two, between a monocotyledon and a dicot. Often the limits of
what can be grafted have to do with how the various tissues are organized and
how plant hormones mesh. It doesn't depend on genetic closeness.
After all, we are all related--plants AND animals. There are just so many
ways the systems of how cells do what they do can function. The basic
chemistries of all living organisms have much in common, and in many cases are
precisely identical or so nearly so as not to matter in how certain things get
After what I wrote about Pelargoniums, I remembered why they were chimeras.
The xylem and phloem cell origins of roots and stems are reversed. In the
cases where the geraniums are chimeras, the xylem (stem tissues) and phloem
(bark tissues) are genetically different, although the plant came from a
single seed. The roots of those plants have the genetic individual that makes
up the above ground xylem as the root phloem, with the same reversal of the
other zone of tissue. Thus, cuttings generated from roots and stems have the
opposite array of which tissue is where.
Broken color irises may not be chimeras. BC is a variant on the plicata
locus, is it not? BC irises sometimes have plicata wedges in the flower, such
as a substantial section of a fall. Similar segments occur in other plicata
alleles and mixes of alleles in varieties. Although I have one BC, I am not
especially familiar with them, and not at all drawn to them. Several of the
'Honorabile' sports seem to me to be chimeras, as the wedges of color variance
are different from flower to flower. 'Kalaidoscope,' 'Joseph's Coat
Katkamier' and a number of others of which I don't recall names exhibit the
variability of which I'm writing. I don't think these are the same as BC
Bill Burleson commented in an e-mail after the "Chimera" post about the
daylilies including both diploid and tetraploid tissues in the first
conversions. He said that one just pollenated flowers as they came. The
resulting diploid and tetraploid offspring would be significantly different.
One did not need to be selective in which blooms to pollenate. The occasional
triploid wasn't hard to recognize--it was sterile. Bill--correct this if I
have misrepresented what you said.
Neil Mogensen z 7 western NC mountains
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