Re: fertility of mixed crosses with aphylla based iris

We have been breeding with counted 48 c aphylla species since 1967. We 
have made thousands of crosses over the ensuing years. Our crosses have 
been made, with few exceptions, with tet 48c TB's. Over the years we 
have crossed our aphylla X  TB seedlings with other aphylla x TB 
seedlings maintaining the 48c genetically.  We now have a huge variety 
of iris which fit everything from the SDB class to TB's out of our 
breeding program. Nearly all are 48 C. All are fertile.  The exception 
is once in a while we cross to SDB's and diploid (24C) iris  and 
occasionally cross their seedlings to our 48c seedlings.   If you doubt 
the ploidy of our iris you are most welcome to have them counted. We 
will always report on an iris if it has mixed chromosomes.
Pumilas are 32 chromosome tetraploids. Modern Tall Bearded are 48 C . 
Most aphylla are 48C but there are known to be at least one 24c which we 
do not have. Plus at least one collected species has been found to have 
40 C and is considered to be a 'bee' cross in the wild. Pumilla X TB = 
SDB-MDB 8-8-12-12 c =40C   Crossing the 32 C tet with the 48 C tet does 
not make a tetraploid. It becomes an amphi-diploid. (A double diploid 
carrying two sets of chromosomes of different counts, too different to 
pair together,  forcing each to only pair with it's own partner.)
Hope this helps you  understand our breeding program.
Vicki




 
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