R. multibracteata

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philip_la
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R. multibracteata

Post: # 67088Post philip_la
Wed Feb 14, 2018 9:30 pm

Has anybody worked with this species? I found it in the distant pedigree of a few intriguing cultivars, and I'm wondering what the species offers to progeny. It's tetraploid to boot. I like the look of the species itself.
Philip F.
[size=small][color=#669966]Zone 8 / Sunset Zn 30 (Austin, TX -- formerly New Orleans, LA)[/color][/size]

Karl K
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Re: R. multibracteata

Post: # 67090Post Karl K
Thu Feb 15, 2018 10:31 am

philip_la wrote:Has anybody worked with this species? I found it in the distant pedigree of a few intriguing cultivars, and I'm wondering what the species offers to progeny. It's tetraploid to boot. I like the look of the species itself.
Tantau crossed it with 'Crimson Glory' to get 'Cerise Bouquet'.
http://www.helpmefind.com/gardening/l.php?l=2.34784

Wulff (1954) discussed the influence of R. multibracteata and R. roxburghii in a paper that is not entirely clear.
"Mr. Tantau sen., on the other hand, chose a hybrid tea rose "X" (the true name of which cannot be given here) for the cross with Rosa multibracteata and, in 1938, got a hybrid "A" which was similar to the male parent in most characters, but the flower was double and beautifully red-coloured."
http://bulbnrose.x10.mx/Roses/breeding/ ... rghii.html

I had guessed that "A" was 'Crimson Glory', but the parentage is reversed. Maybe one of the sources is wrong.

At any rate, it does appear that R. multibracteata has entered the gene-pool of modern roses to some extent. If you want to work with this line, it would be quicker to start with 'Cerise Bouquet' rather than the "pure" species because not all potential parents will be successful with it. Wulff wrote, "Mr. Kordes succeeded in crossing his 'Baby Château' with Rosa multibracteata, but the double flowers of the hybrid did not open at all and produced no or only a few anthers."
Karl

Don
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Re: R. multibracteata

Post: # 67093Post Don
Thu Feb 15, 2018 11:30 pm

There is a phenomenon in wide crosses such as 'whatever x roxburghii' where the resultant embryo drops the chromosomes of one parent and replaces them with a duplicate of the other while potentially doubling those chromosomes in the process. I forget what it is called but iirc there is a paper in Karl's collection that discusses it and, if it happens, it provides a sort of magic bullet for amplifying the genes of whichever parent's chromosomes survive by a factor of two. This would give you twice the expression of whichever traits the duplicated chromosomes produce. In the case of Tantau, I conjecture it was twice the anthocyanins and petalage of Baby Chateau.

With that in mind, I accepted an offer of two cultivars of roxburghii from Quarryhill about ten years ago to see if I could produce the effect. It turned out to be a pain to get a fruitful cross out of roxburghii and a modern rose. The only one that took was with Carefree Delight, and I have only two seedlings from that cross. Moreover, they are clearly hybrids that retain compliments from both parents. Both are female sterile and I have not used their pollen enough to have any f2 seedlings.

I mention this because I think it was roxburghii rather than multibracteata that was parent of Tantau's roxburghii hybrids and, if you want to go down that path for whatever reason, suggest you cast a wide net and be patient.
What doesn't kill them makes them stronger.

philip_la
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Re: R. multibracteata

Post: # 67094Post philip_la
Fri Feb 16, 2018 12:16 am

I was rather hoping that multibracteata might breed like a tetraploid rugosa, to which it is somewhat related, being in the sub-section cinnomomeae. I, however, have zero familiarity with this species.

I don't recall the hybrid purportedly having an unnamed descendant of multibracteata in its lineage which instigated my research. It was not Cerise Bouquet, though that is the only one that came up in a subsequent advanced search.

I believe that Roxburghii is in a unique sub-section Platyrhodon. I wonder if that affects compatibility and thus forces the issue of chromosomal replacement?

Admittedly, when I start trying to talk phylogeny, I am wading in *way* over my head, and don't know to what extent it even matters.
Philip F.
[size=small][color=#669966]Zone 8 / Sunset Zn 30 (Austin, TX -- formerly New Orleans, LA)[/color][/size]

Karl K
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Re: R. multibracteata

Post: # 67106Post Karl K
Sat Feb 17, 2018 8:58 pm

Don wrote:There is a phenomenon in wide crosses such as 'whatever x roxburghii' where the resultant embryo drops the chromosomes of one parent and replaces them with a duplicate of the other while potentially doubling those chromosomes in the process. I forget what it is called but iirc there is a paper in Karl's collection that discusses it and, if it happens, it provides a sort of magic bullet for amplifying the genes of whichever parent's chromosomes survive by a factor of two. This would give you twice the expression of whichever traits the duplicated chromosomes produce. In the case of Tantau, I conjecture it was twice the anthocyanins and petalage of Baby Chateau.
Do you mean parthenogenesis? It can happen. However, with more sensitive tests and closer examinations, some of the supposed cases have turned out to be not so virginal.

In some cases, seedlings look like proper hybrids, but have chromosomes of only the seed parent. In other cases, the plants are overwhelmingly similar to the seed parent, but are found to contain snippets of DNA from the pollen parent. There is quite an assortment of these odd cases.
http://bulbnrose.x10.mx/Heredity/King/E ... osses.html
Today I added a couple of new items. Check out these oddities:
de Wet: Counterfeit Hybridization and Speciation (1984b)
Wimber: Phragmipaphiums (1985)

I can't find the source, but I read years ago that Tantau's three Baby Chateau x R. roxburghii offspring are remarkable for their disease resistance. Tantau chose 'Baby Chateau' for its free flowering. The disease resistance must have come from Roxburghii.

Then there's this:
Research Highlights, vol. 51. Experiment Station, 1988 p. 98
Roses growing well, by Regina Broadway
"The chestnut species rose, Rosa Roxburghii, is completely resistant to blackspot, and at times seems to have a strange leaf surface cell type,” Spencer explains. "It may release chemicals that inactivate the fungus spores."

This is possibly the same resistance that was handed down to 'Tropicana', making it one of the healthiest roses in the U.S. (ca. 1985) ... until that Tropicana-loving strain of mildew knocked it off its pedestal.
Karl

Karl K
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Re: R. multibracteata

Post: # 67125Post Karl K
Mon Feb 19, 2018 11:15 am

Don wrote:There is a phenomenon in wide crosses such as 'whatever x roxburghii' where the resultant embryo drops the chromosomes of one parent and replaces them with a duplicate of the other while potentially doubling those chromosomes in the process.
Don,
There was another item about R. roxburghii that I had trouble finding. But there it was on my web page.
Hurst (1928)
"Platyrhodon microphylla, from China and Japan, the so-called Chestnut Rose with cup-shaped fruits covered with fleshy spines, seems more promising in its fertility since I have succeeded in raising the second generation of a cross with Rosa rugosa. The results, however, although extremely interesting from the scientific point of view, are not very promising horticulturally, since the grandparent R. rugosa has been reproduced in facsimile several times, while the others resemble the parent hybrid with strange mutational variations."
http://bulbnrose.x10.mx/Roses/Hurst/Hurst_1928.html

This hybrid does look like a hybrid. I have seen 'Walter Butt', a once-bloomer with silvery-pink flowers. The leaves, canes and hips indicate the dual ancestry. However, as Hurst's account suggests, roxburghii is not so fully represented in the hybrid that none of the self-progeny could incline towards it.

Graham Stuart Thomas added this:
"During his experimental work with the parentage of roses at Cambridge in the second quarter of this century, Dr C.C. Hurst raised seedlings of this cross, one of which was named R. x micrugosa 'Alba'. Apart from being of rather more upright habit, it is in other respects a replica of the original but of important garden value because the white flowers are produced not only at midsummer, but onwards throughout the growing season. They are, moreover, very fragrant. This might prove to to be a fertile parent and thus bring both species into today's hybrids. They would be very hardy."

A bit off topic, while I was looking up the Phragmipaphium business, I found a mention of Professor Charles Hurst. It took me a couple of seconds to recognize the man I had always known as C. C. Hurst.
Karl

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