Are there any species of roses that, while common, have never been experimented with greatly? I’m interested in diversifying the roses used in the garden. Particularly, I’d love to incorporate the blood of American roses (r. nitida, r. arkan. , r. vir. , r. car. , etc.).
On a side note, do the other yellow Asian roses (r. hugonis, r. xanthina, r. ecae) suffer from blackspot? I would also be interested in finding a way to bring in yellow/orange color with more blackspot resistance.
Finally, what are the merits of r. filipes? I seem to recall a descendant producing some unusual curved petals.
I love your idea of using American species. Please be aware that they seem to depend upon Rust to indicate when they should defoliate and prepare their Arctic hardiness for “winter”. The hybrids of them have been quite prone to rust in my experience, particularly water stress induced rust. If that disease isn’t an issue where you live or where you hope your roses to find loving homes, then it shouldn’t be an issue you might consider. I have grown many of the Arkansana hybrids and the only one which didn’t rust for me was Morden Blush. Black spot hasn’t been an issue where I’ve grown roses (thankfully!).
R. Primula, Hugonis and Xanthina do develop bronzy colored “spots” on the aging foliage prior to shedding it, but I’m not so sure it’s “black spot” or not as, again, that isn’t a traditional issue here.
Hugonis and Xanthina get something here (sydney, australia) too but only at the dscarding leaf time (ie leaf is shaded out so it’s inefficient for photosynthesis or during fall), comparable to Golden Cheronese so not bad, no early defoliation just not the prettiest when discarding leaves. Having said that my plants Hugonis and Xanthina are seed grown (near impossible to get grown plants here), not all of them get spotting. Hugonis seems more prone than Xanthina on average. Given the limited window the spots turn up, I’d be inclined to think it’s not blackspot.
Ecae never germinated for me and haven’t found a seed source since.
Speaking on Ecae, there is a theory on these forums in an older discussion that the deeper yellow pigment from it might only pass via seed. I don’t know if anyone was able to confirm it but something to consider https://www.rosebreeders.org/forum/viewtopic.php?f=2&t=30065
I wouldn’t be surprised if the spotting is their equivalent of Arkansana, Virginiana, etc. rusting just prior to leaf drop to prepare for cold. Fortunately, Hugonis has a bronze pigment to it so the spotting shows up in that range rather than ugly “black spot”. Until it’s that leaf drop time, it remains clean for me. Xanthina remains better looking for me. Dr. Byrne at TAMU brought back seed from China and sent it to me. There was too much so I shared it with Joe Bergeson. I kept two of my seedlings. I shared one of them with Jim Sproul. Primula has that marvelously scented foliage which is pretty much of the year, but looks the worst of the bunch toward the end.
R. xanthina has perhaps my favorite name. As a kid I read a series of fantasy books by Piers Anthony set in a fictional country named “Xanth.”
Alas, my seedlings of R. xanthina died back too far each winter here in Zone 3b to ever get more than a smattering of blossoms, so I removed them.
I think every discussion of rose species needs to be accompanied by a great big disclaimer. Genetic variation and the potential for mislabeling even at the wholesale level make it very likely that your rose of a particular species and my specimen of that species are different enough to be considered apples and oranges.
For instance, the rose that I ordered from Forest Farm as R. davidii is most likely NOT R. davidii. With the help of folks here on the forum I’ve come to the tentative conclusion that it is actually R. davurica. It has thin, willowy, upright stems that are hardy to the tiniest tip. My specimen has been healthy enough that it appears to compare favorably to R. woodsii and R. acicularis (diploid form) while having similar hardiness and habit.
R. woodsii might offer a path towards hardiness and thornlessness together. I have some selections that are nearly thornless. They generally get some foliage ugliness later in the season that might be cercospora. (My roses that I call R. woodsii came from Lawyer Nurseries, as did my R. acicularis which appear diploid and are very different from Robert Erskine’s ‘Aurora’, which was supposedly a wild R. acicularis.)
R. nitita is an amazing diploid species that really adds hardiness even as a diploid crossed with modern polyploids and has more modern glossy foliage. My new favorite North American species to play with. David Z mentioned problems with mildew in the Minneapolis area, but my specimen (can’t remember where I got it…maybe Rogue Valley) has not shown any mildew.
My R. virginiana and R. carolina came from Lawyer Nursery and are basically indistiguishable so I think they’re all one or the other. Very good for adding vigor to modern roses, and I think health as well. They say R. virginiana is not such a “yellow-killer” as other species…easier to keep yellow shades in crosses with modern yellows…and in my experience that may be true. It’s going to be harder to regain rebloom using tetraploid species like this than with R. nitida.
R. arkansana sucks, in my experience. (see above disclaimer)
David Zlesak has worked with R. setigera in an attempt to incorporate resistance to Rose Rosette Disease. Make sure to read about cryptic dioeciousness (if that’s the right term) before starting down that path.