Does anyone know the ploidy of Isabella Skinner (Victorian Memory). I’m not finding much online.
Thanks!
Tony
Without knowing the ploidies of the “tea” and the “floribunda” listed in its parentage, we can’t really know without checking the ploidy of ‘Isabella Skinner’.
My guess would be that it’s either triploid or (less likely but not unlikely) diploid. Rosa laxa Retzius is diploid.
Does anyone know whether it sets OP hips?
Peter
Thanks Peter! Diploid would be nice. Triploid would be problematic…
Tony
Isabella Skinner set few hips in my Newhall garden back in the early to mid nineties and they had few seeds which never germinated. Nothing I ever put on her took, nor did her pollen work on anything I tried it on. Not that it means anything as seed set is highly location and climate dependent. Iceberg and Mermaid seldom set hips in the inland valley heat, but both set them in the cool, damp coastal conditions.
I just got one in the mail this week. I can look at the pollen under a microscope when mine blooms and maybe make a guess as to the ploidy based upon the pollen.
Thanks for the info Kim!
And thanks for checking out the pollen Joe!
Tony
Peter, my IS has not. So far crosses self terminate showing yellowing of the hip “stem” and failed hip. But not stopping on trying until acquire a R. Laxa R… Agatha another super - hardy (in my garden) has the same issue for me. Spino hardies rampant hippers.
From what Kim and Riku have said, I’d guess that Isabella Skinner is triploid or at least of very confused ploidy. The pollen might work on an “easy” mother.
Peter
Joe - I thought of a question for you. I know there’s some correlation between ploidy and relative size of pollen grains, but are there a Genera-wide averages for pollen size vs. ploidy level?
Tony
Hi Tony,
There have been discussions about that here before and others might know more than me. I suspect different species or groups of roses might have pollen of different sizes, as well as the difference from ploidy. My pocket microscope (or maybe it’s operator) doesn’t have measurement capabilities, so I’m like “oooh, those are some fat grains, must be tetraploid.”
I’ve posted my microscope on here before…it’s really fun to have one and they’re less than $15 on Amazon, I think. Don’t waste your money on a digital one. You’d think a digital microscope could overlay a measurement grid but I’ve bought several and they just didn’t have as good of a resolution and I couldn’t figure out how to measure with them.
By the way, all this talk of pollen diameter bothers me. Is it length or width? I suppose it’s width, but all pollen grains are oval and the proportion of length to width varies.
The most useful aspect for me is looking at the pollen of likely or possible triploids. Triploids will almost always have pollen of varying sizes. The pollen of a pollen-sterile rose will look like a bunch of misshapen globs, but if you spot some of the plump egg-shaped grains you know that it will have some fertile pollen. If all the grains are uniform and healthy, you likely have a diploid or tetraploid. Looking at the pollen of a known diploid such as a rugosa cultivar will give a size comparison.
I just collected pollen last night from some R. nitida x modern polyploid seedlings and am about to check it out under the microscope. Fun!
Joe
By the way, the black, slightly textured surface of a coffee can lid is perfect for looking at pollen under a microscope.
Just looked at my pollen…all three nitida hybrids had good pollen grains of mixed sizes. It’s easy to see why the 2x pollen has a competitive advantage. One of my likely tetraploid roses had very fat (closer to being round) grains. Cuthbert Grant had relatively poor looking pollen but maybe some viable grains. The Ann Endt x polyploid cross didn’t release any pollen at all.
Thanks Joe!
That does sound like fun! I might have to get me one of those hand-held microscopes. I can use the full-sized scopes at work, but that not quite the same.
Tony
…and I look forward to hearing what you see when you look at the Isabella Skinner pollen!