HYB: Fertility and chromosome count for Swertii please
Steve, Swertii is almost certainly diploid as it dates from the 1600's. I've
not seen it listed among varieties that are counted, but the possibility it
could be tetraploid is vanishingly small.
I have never grown the variety, but most *pallida* kindred are typically pod
fertile, with some pollen sterility scattered around.
Swertii appears to be one of those advanced generation hybrid forms from mixed
*pallida* and *variegata* forms. No one has any idea how many generations of
hybrid mix is involved in the wild swarms in Europe, but there is reason to
believe these swarms have persisted for many centuries if not millenia.
I'm assuming the cv emerges from a very long line of development, mostly under
natural conditions, as it is a collected form.. At 30" the height alone
suggests some *variegata* admixture, although the flower more closely
resembles some *pallida* forms. Plicatas in general seem to be more from
*pallida* ancestry than from *variegata* origens.
Even though first generation hybrids between clones of the various diploid
pure species clones often have very limited fertility in my experience--some
being completely sterile, this does not seem to be the case in the advanced
If you do try crosses with tetraploid pollen parents, it may be helpful to
note there have been suggestions that plants under stress have somewhat higher
probability of producing offspring
The second suggestion is to use Swertii as the pod parent if possible if you
are after a tetraploid conversion. The probability of catching an
impregnating an unreduced gamete is greater in using the diploid as the
maternal parent compared to the reverse, Success is not unknown from the
diploid as papa, as in the ancestry of SNOW FLURRY from Purissima X the
Purissima is not known to produce pollen, so the cross is certain to be true.
The phenotype of Snow Flurry also tends to confirm the ancestry.
If your goal involves continuing on the diploid level, the problems resulting
from contrasing ploidy is not going to arise.
The tucked and pinched form of the falls on Swertii may tend to plague the
hybridizer for generations, as these are very difficult characteristics to
eliminate from a line. The choice of wide, flaring or semi-flaring,
non-pinched co-parents may be very important.
Neil Mogensen z 7 western NC mountains
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