Rosa Pomifera is a Caninae section species which typically is tetraploid. It should have 3 sets of chromosomes in the egg and one in the pollen due to being a Caninae section species. I obtained a 3x seedling through parthenogenesis. This 3x seedling is quite fertile and selfs readily. The limited number of these selfs I confirmed are also 3x. So, it may be producing 2x eggs and 1x pollen. This is very interesting in light of some recent report describing the two chromosome sets which pair in order to produce the 1x pollen in general in Caninae section species are very similar and preferentially pair. This 3x fertile R. pomifera seedling may suggest that another set of chromosomes or various homologs can substitute for one of these sets which typically preferentially pair. In any case, crossing these triploids as females with 4x modern roses will probably produce tetraploid hybrids having half R. pomifera chromosomes. If one used the standard tetraploid species that one would offer 3 sets of R. pomifera in the egg. It may be easier to develop repeat blooming descendants by limiting the female contribution of R. pomifera genes using these triploids.
R. pomifera is shade tolerant, hardy, has velvety fragrant leaves, and is an early bloomer. It may produce some very unique hybrids. In addition, the orginal 3x hybrid and its seedlings seem more vigorous than 4x plants. This may be due to a reduction in ploidy and faster growth rates conferred by reduced ploidy. Increased ploidy is often associated with larger plant parts, but also at times reduced growth rates.
If you would like some seedlings of this 3x R. pomifera (selfs- very early bloomer and only thing in bloom at the time), please contact me with your name and mailing address. zlesak@rocketmail.com The seedlings are in 6-packs now. I’ll try to send each person a few plants. I think these seedlings are a great resource and have more than I can handle.
Sincerely,
David Zlesak