Re: SPEC: Intergeneric hybrids

From: Bill Shear <BILLS@hsc.edu>

If we assume for purposes of argument that Pardanthopsis is a separate
genus, are there any known hybrids between members of the genus Iris (taken
broadly, not the Rodionenko version) and any other genus of Iridaceae?

I do not know of any.  By known hybrids, I mean plants that have been
certified as such by their intermediate character or by chromosome or DNA
analysis, and that are still in existance or documented by herbarium
specimens or photographs.

Only if Pardanthopsis is folded back into Iris can we claim any
intergeneric hybrids for Iris--Iris dichotoma with Belamcanda chinensis.

There also appear to be "inviolate" groups within the genus.  We don't have
any existing certifiable hybrids between beardless and bearded irises (not
including crested irises in beardless; they're obviously closer to the
bearded irises), and none between bulbous irises and rhizomatous irises.
Bearded irises, arils and crested irises seem to form a slightly
interfertile group, with the crested irises somewhat distant from the other
two.  Laevigatas have evidently at least some limited fertility with
hexagonas and perhaps foetidissima (Holden Clough?), in each case through
the promiscuous I. pseudacorus, but not with siberians and PCNs, which are
relatively interfertile and also cross with setosa, although with more
difficulty.  Christy Hensler has reported ensata/siberica hybrids, but the
jury is still out on that one.  Spurias seem to stand alone.

Now, if one reads the GUIDE TO SPECIES IRISES published by BIS, one finds
listed all manner of extremely wide crosses, many violating the suggested
fertility groups above, and even including some intergeneric crosses.  But
where are these hybrids today?  Is herbarium material or photography
available?

I'm very, very skeptical of wide-cross hybrids that are casually reported
or that do not show intermediacy between the purported parents either in
appearance or chromosome numbers.  My eyebrows are further raised when the
cross is reported as "easy" or large numbers of seed are produced.

This isn't meant to impugn anybody's honesty, but just represents the "show
me" attitude that keeps science self-correcting.  So I'll believe in the
Dietes/Iris crosses when I see the offspring.

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

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