Re: Re: TB, lumis, plics, Silverado

Christian,

Yes, there are two different kinds of plain white iris that are not plicata,
luminata or glaciata, or at least not visibly so.

The majority of white, pink, yellow, or orange iris (remember Keith Keppel's
"canvas") carry a genetic factor which interupts the synthesis of the
blue-violet pigment.  The symbol usually used for this is "I" (that's an
'eye') for "Inhibitor."

A few whites (or, rather, non-blues/violets) do not have the genetic capacity
to form the blue-violet pigment and thus are white (or yellow, pink, etc.).
These are recessive whites.  Recessive whites do not look like glaciatas--they
do have some haft marks.  Glaciatas do not.

The problem with the "I" whites is that "I" does not prevent the formation of
*some" blue-violet pigments, so varieties such as *Silverado* --which IS a
dominant "I" white--end up ice blue or light blue-violet in spite of the
inhibitor.  You might note that the parentage of Silverado is (orchid x dark
violet from blue and black breeding) X white (dominant type).  The pigments
involved in the blacks tend to penetrate through the "I" factor.  They are a
bit different from ordianry Iris blue-violet and presumably come from I.
aphylla.

Does this help?

Neil Mogensen  z 6b/7a near ice-box Asheville where it just barely got above
freezing today

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