I have developed two new Rosa rugosa hybrids that bloomed for the first time this year. They may have potential for further breeding. The first is a ‘Ottawa’ x Rosa wichuriana with single, mauve pink flowers about 5 cm in diameter. The direction of the cross is probably the same as ‘Max Graf’, but in comparison the shrub appears to be more upright. ‘Max Graf’, of course, is almost sterile as a pistillate parent. I am hoping that my Rosa rugosa/wichuriana will not be sterile so that it can be used for further breeding to develop new types of roses.
The second is a ‘Hansa’ x Rosa foliolosa with semi-double, purplish red flowers somewhat lighter than ‘Basye’s Purple’. Again, I am hoping it will be fertile for further breeding.
Rosa rugosa has endless possibilities to develop new types of roses, since as a pistillate parent it has the ability to accept pollen from a wide range of species. It is only too bad that Rosa rugosa (a diplolid) hasn’t been developed to any extent at the tetraploid level. Then we would quickly see major progress in developing Rosa rugosa hybrids of high quality.
By “Tetraploids” one can assume you talk about big-flowered classic garden roses.
Many attemps have been done since the end of the 19th Century.
Gravereaux and his friend the Dr M
I think Henry Kuska’s site has a link to an article about tetraploidy and rugosa. I believe that those tetraploid versions of rugosa had a lot of fertility problems. Concerning the use of rugosa in the improvement of tetraploid modern roses, I feel like Dr Basye had the right idea – to combine rugosa with other diploid species, convert the hybrids to amphidiploidy and then interbreed those with the modern tetraploids. This approach has a good precedent – Rosa kordesii (derived from rugosa and wichuraiana, spontaneously chromosome doubled) and all of its great offspring. I realize this is a somewhat slow and difficult (chromosome doubling) process, but I think it can yield great results.
I have a probable tetraploid rugosa seedling. It appears to be “pure” rugosa. It is very female fertile, but its offspring have very little rugosa influence. I hope to try crosses next year using pollen parents that have some rugosa background. It may be more difficult than it sounds to get obvious rugosa traits into a tetraploid line. I do have extra OP seed if anyone wants some. Most OP seedlings are rugose.
[PS–Paul, please contact me.]
Conrad Ferdinand Meyer (rugosa hybrid x Gloire de Dijon) has been counted as a full tetraploid. I grew it decades ago. It does not show much rugosa characteristics except more prickles, rounder leaflets and large growth.
Rugosa was converted to tetraploidy years ago and hybrids from these converted tetraploids and modern roses were released as breeding tools about twenty years ago.
Pierre, I assume that you are referring to the “Spotless” series released by Beltsville.
My understanding (from old Rose Hybridizers Newsletter messages) is that people tried them and ran into the same problem Joan and I have found. This year I have tried a number of crosses with Kordessii type roses (German and Canadian) which of course already contain rugosa blood.
I am still working on remodeling the sunroom which I had used as a greenhouse until black mold struck. This will take another week or so. Then I will start harvesting hips. I have observed that the tetraploid rugosa - Dortman croses did not take (unexpected). I do not know if that was due to the pollen being too old or the temperature being too high when they were used.
One tetraploid Sir Thomas Lipton hip (with Simon Fraser pollen) has a great big ripe hip (much larger than the open pollinated hips).
Regarding the problem of wide rugosa crosses lacking vigor and/or disease resistance and/or fertility. In looking at the history of rose hybridizing, I came across several examples where a species was difficult to breed with more desired forms of roses until a “bridging cross” was discovered.
One possibility of such a cross with rugosas may be Therese Bauer ((Hansa X R. setigera) X R. setigera):
I have a number of open pollinated seedlings that appear to have considerable rugosa influence and are fertile, winter hardy, disease resistant, and vigorous.
Regarding the term tetraploid rugosas, I am referring to three types. Diploid hybrids converted to amphidiploids, rugosas that have their chromosomes artificially doubled by colchicine and rugosas crossed with hexaploids that result in tetraploids. A rugosa hybrid like ‘Conrad F. Meyer’ I don’t think of as a rugosa, because in this case it probably only has 25% rugosa at the most. Again, not enough work has been done to develop these types of tetraploid rugosas, and until they are we don’t know the potential for developing hardy, disease roses of high quality. Because of their relatively good disease resistance, I would think that Rosa kordesii hybrids would have the most potential to breed with tetraploid rugosas. This year I crossed ‘Hansa’ with ‘John Cabot’, and while the progeny will be triploids it will be interesting to see how hardy and disease resistant they will be.
Yes it was these “spotless” roses with little evidence of rugosa.
Your Therese Bauer seedlings are quite exciting: nice and clean.
Could not find TB in CRL… may I beg some OP seeds?
I agree there is untaped potential in rugosa. Kordes and other germans decades ago did advanced rugosa crosses and got some frost resistance. Kordes is annually releasing various ploidy rugosa hybrids with rather high desease resistance.
I have two plants coming from an OP of “Damask” St Nicholas. Both have a somewhat rugosa foliage… One (unflowered) looks like really as a rugosa…
so: - maybe there is a Rugosa parentage in St Nicholas
- maybe it can be used as a rugosa hybrid, giving rugosa type seedlings???
your opinion is welcome!
Pierre Rutten, yes, I can try to send you some seeds; but even if our post office allows them to be sent, you will still have to take care of whatever import rules your country has. For my part I will clean them, dip them in hydrogen peroxide, and clearly mark the package as containing rose seeds.
(10 years or so ago, I used to exchange rose seeds freely with people from other countries; but since then, both the U.S. and some other countries have imposed new restrictions.)