First, I want to apologize for not being able to use the built-in quote function, or italics, or any of the other text controls; for some reason all I get is code mixed in with my text when I try to use it.
philip_la wrote, “I don’t know if R. maximowicziana has the same inclination for RRD as the multifloras, but even if so, it seems there could be other arguments (e.g. hardiness) for choosing max. over multi. as well. (Does one seem to show greater resistance to common diseases?) If one were to use some of the hardier repeating Kordesii lines in the mix, it seems like there could be a decent possibility of getting some healthy zn 3/4 hardy reblooming climbers within a few generations, no?”
Me: ‘White Mountains’ has been reported to be resistant (immune?) to either RRD or the mite vector, so that could be an indication, if true, that R. maximowicziana is also not susceptible. Neither R. maximowicziana nor R. setigera is in any sense disease-free in the hot, humid Mid-Atlantic (R. multiflora is much healthier), but they are both tough and shrug off their spots and continue to plot world domination. For whatever it’s worth, I have two seedlings of ‘Baltimore Belle’ x ‘White Mountains’ that are vigorous to a fault and not unattractive, although they’ve inherited the latter parent’s complete lack of scent. They put on quite a show when they bloom but I’ll admit they annoy me most of the rest of the time with their excessive growth, and they definitely aren’t thornless… None of those has shown any signs of contracting RRD, not that you could draw any definite conclusions from that. The real question is, how hardy is R. maximowicziana compared with R. setigera (at least those of more northern provenance) or R. multiflora (which can survive well into zone 4, if not actually thrive there)? I’m not sure I’d give it the benefit of the doubt in such a comparison without real observational data.
Karl K wrote, “Has anyone considered building a new R. Kordesii using R. Maximowicziana instead of R. Wichuraiana? One might even go so far as to use a form of R. rugosa from Korea or further north. Or ‘Hansa’, which reportedly flowers freely in Alaska.”
You could recreate a sort of ‘Max Graf’ (and maybe then a version of R. x kordesii) using R. maximowicziana and a hardier (likely hybrid, R. x kamtschatica, which probably accounts for the hardier Russian “R. rugosa” stock)… but I shudder to think of the even greater number of prickles you’d then have to overcome, and unless the R. rugosa contributes enough to dominate the hybrid, disease resistance might not be what you get with R. x kordesii, since R. maximowicziana is not as healthy as R. lucieae (the correct current name for R. wichurana, FWIW.) Maybe more thorniness is an acceptable trade-off for somewhat greater hardiness… or you could try crossing R. maximowicziana first with the thornless form of R. lucieae (assuming that trait is dominant–I think it might be), screening for hardiness, and then crossing the more useful progeny with R. rugosa would help tame the prickles.
Karl K (also) wrote , "That is probably true in general, but I’ve seen the occasional exception, such as the IAC Rose described by Budd & Hansen (1896). (in response to my statement, “petal count is considered to be a quantitative trait.”)
"One thing that comes to mind is that various Rosa species differ in their numbers of stamens, which are transformed into petals by “doubling”. For example, according to Erlanson (1934), Rosa woodsii averages 65 stamens. R. blanda, on the other hand, has from 85 to 140. If specimens of both species were crossed with a China rose, with cross is likely to have offspring with more petals?
Then there is R. palustris with more than 200 stamens per flower, if you really want to pack in the petals."
Me: Karl, I also agree that there are exceptions to a lot of the genetic “rules” we’ve been taught, if not all of them… it was admittedly pretty lazy of me to repeat dogma like that without qualifying it. There certainly are known examples of double-flowered roses with single-flowered parents, like ‘Baltimore Belle’, which almost certainly was raised from seed of some single-flowered R. setigera. That said, I do wonder if some apparent exceptions might not have alternate explanations or mitigating circumstances–for instance, “Russian” R. rugosa stock might really be a hybrid, such as R. x kamtschatica, and a mixed background might permit the other parent to have greater apparent dominance in any offspring. Also, that particular hybrid would likely have double the chromosomes from tetraploid ‘General Jacqueminot’ as from the diploid rugosa parent, so that might also have some influence over the resulting seedling’s petal count.
I’ve also wondered whether petal count is limited by the number of stamens that are naturally possible… I’m not sure it’s that clear-cut, and some experiments would really need to be conducted. (I’m not necessarily volunteering…)
Karl K (one last time) wrote, "I’ve been wondering how the reblooming Scotch rose group has fared in the far north.
‘Stanwell Perpetual’ is an oldie that has been recommended for northern Sweden. It seems to be a stubborn parent, as it stands it could be trained upwards as a climber. I’ve seen it, but haven’t grown it.
‘Ormiston Roy’ looks like a nice little bush with a little late bloom. Apparently that’s enough because 'Golden Wing’s [Soeur Thérèse x (R. spinosissima altaica x Ormiston Roy)] is a reliable rebloomer. Maybe GW isn’t hardy enough for the far north, but I’m guessing that (R. spinosissima altaica x Ormiston Roy) would make a good breeder. Or maybe (Hazeldean x Ormiston Roy).
Then there’s ‘Doorenbos Selection’, a reblooming Scotch rose with wine-red flowers. I have seen it in San Jose, CA, where the winters are not at all challenging. If it is hardy enough in the north, it might be used to breed a companion to ‘Stanwell Perpetual’. Otherwise, paired with R. altaica, it might yield a breeder to go with the (Altaica x Ormiston Roy) cross."
Me: ‘Stanwell Perpetual’ generally had some winter dieback each year for me in zone 4 Minnesota, although it was still able to flower (poorly, in no small part because it was an own-root specimen, and this cultivar really does both flower and repeat better when grafted.) If you can find it, ‘Ormiston Roy’ might be useful; ‘Golden Wings’ was not very cane hardy in zone 4, and the best thing I can say is that it lasted for a few years as a dieback shrub. The only seedling of ‘Doorenbos Selection’ I’ve grown, which was probably pollinated by ‘Harison’s Yellow’ (it was OP), didn’t inherit any repeat bloom–but then I don’t think that ‘Doorenbos Selection’ has ever had more than a very light sprinkling of repeat flowering here. My patch of that cultivar has now probably completely died out (I have horrible luck keeping R. spinosissima and its hybrids alive here for very long, even though they grow and spread like wildfire before suddenly declining.)
Whew. Once again, I apologize for my lack of quoting/etc. abilities. I need to figure out what’s wrong. (Help?)
Stefan
