R. Glauca X Frontenac

I have a few seedlings this year from R. Glauca X Frontenac and three of them are green and have R.wichuraiana type foilage. The first one has the shape of Frontenac with short internodes, the second has trailing thornless canes, and the third is inbetween the other two, not trailing(yet) but with longer canes than the short internode one. My question is how in the world did this come out of R. Glauca if R. Glauca is suppose to furnish 75% of dna and Frontenac 25%. R. Wichuraiana is in the ancestery of Frontenac but not real close and then had to overcome the R. Glauca dominance.


Wide crosses often bring out unexpected characteristics. This is why determining hybridity can be so difficult.

In this case glauca is seed parent, so there’s no question of hybridity.

“What you see, is what you get.”


You said- “R. Glauca is suppose to furnish 75% of dna and Frontenac 25%”?

How does this happen?


George, do a site search for caninae meiosis. There’s a lot of information from past discussions.

“R. Glauca is suppose to furnish 75% of dna and Frontenac 25%”?

“How does this happen?”


There are others here who can explain this much better than I, but here goes. Most modern garden roses are tetraploid, with 28 chromosomes. When used in breeding they furnish 14 chromosomes when used as either seed parent or pollen parent. When both parents are tetraploids, both parents normally furnish 14 chromosomes to their seedlings and the resulting seedlings are also tetraploids, with 14 chromosomes from each parent (50/50). R. glauca is also a tetraploid, but it is member of the Caninae section of roses, which behave most peculiarly when used in breeding. Most roses in this family have either 28, 35 or 42 chromosomes. When used in breeding, they furnish only 7 chromosomes when used as a pollen parent. When used as the seed parent, the remainder of the chromosomes (total minus 7) are furnished to the resulting seedlings. In the case of R. glauca, with 28 chromosomes, this means it will furnish 7 chromosomes to its offspring when used as the pollen parent but will furnish 21 chromosomes to its offspring when used as the seed parent. Since R. glauca is the seed parent in the above cross, it will have furnished 21 chromosomes to this seedling. I do think Patrick’s math is a little off, though. Frontenac is listed as a tetraploid at helpmefind.com, which means that it will have furnished 14 chromosomes to this seedling, not 7. So this seedling will have 21 chromosomes from R. glauca and 14 from Frontenac and will be a pentaploid with 35 chromosomes total. So instead of the 75-25 mentioned above, 3/5 of its genetic material came from R. glauca (21 chromosomes of the total 35) and 2/5 of its genetic material came from Frontenac (14 chromosomes of the total 35).

I hope I haven’t confused you too badly.


Yes… The cross should be pentaploid I guess (triploid glauca seed gamete plus diploid frontenac pollen gamete = pentaploid embryo).

So 60% contribution from glauca, 40% contribution from frontenac.

No wonder the seedlings are confused. Meiosis isn’t always a tidy affair. Roses don’t read books.

A further complication is that of the excess chromosomes in the maternal parent, generally all but one set remain more or less unexpressed, according to some work out of Sweden. So maybe the R. wich dominance isn’t unreasonable. Also, see my article in the most recent RHA newsletter. There is preferential expression of genes from one genome or the other in many instances. So you might get foliage controlled by R Wich and flower by R glauca or who knows what.

Thanks for all your helpful input. I will have fun with these if they are fertile and see if R. glauca traits will come out later on. I wonder what color Pink they will be. :slight_smile: