Working With Species Roses

Have a few questions.

The first is about this list called the septet formulae:

I see several ovum + pollen listings as 3 + 1. Am I correct in assuming that this means that the ovum (seed) will have 3 sets and if pollinated with a diploid of a different species a successful germination would be a tetraploid? If such a cross was plausable, would the resulting child have 3 sets in seed and 1 in pollen or 2 and 2 or any of the above including completely sterile?

At this same website (, is a interesting article by wright about crossing species roses. It states that the more different species introduced into a hybrid, the more of a genetic mess it becomes and that fewer flowers and lower fertility.

What have been peoples experiece with respect to this?

For giggles I ordered a buch of species rose seeds from Chiltern seeds with the intent of some interesting crosses between Hexaploids and Diploids.

I was thinking of things like

(R. Multiflora x R. Nutkana ) x (R. Davurica x R. Nutkana )


(R. Xanthina x R. Nutkana ) x (R. Hugonis x R. Nutkana )

or even

(R Multiflora x (R. Nutkana x R. moyesii holodonta))


(R Filipes x (R. Nutkana x R. sweginzowii))

I have some up with several crosses that are even more convoluted. No goal in these crosses, just a ‘what-if’ type of thinking.

Link: Yahoo | Mail, Weather, Search, Politics, News, Finance, Sports & Videos

It is my understanding that Hurst’s theory is for historical interest only. i.e. it has not been supported by experiments.


Yes the Caninae type species roses typically contribute one set of seven chromosomes as pollen parents but multiple sets (exact # dependent on species) as a seed parent. When selfed (or crossed with another of its own species) you will get the original number of sets again. When hybridizing, you will often get very different results dependent on which direction you do a cross.

Most of the studies I’ve encountered, indicate that this system of inheritance breaks down in hybrids. For instance, the hybrids will give pollen with widely varying numbers of chromosomes. But the Albas (from Rosa canina X tetraploid Old Garden Roses) have six sets (of seven chromosomes) and are supposed to contribute four as seed parent and two as pollen parent. In other words, I think most of this hybridizing area could be considered “uncharted waters” and your own guesses about strategies will be as good as anyone elses.

And since you’re in the “what if” frame of mind, here’s a link to some results from my own species X species playing. My web page is in a sad state of neglect right now, but I figure I can at least share what’s functional right now.

Hope it gives you some more ideas.



I find your rugosa X xanthina to be very interesting. Expecially your note about the seemingly dominant nature of the yellow color from the xanthina parent. R. xanthina is amung the seeds I plan to grow this winter. I will also be getting R. Hugonis.

I wonder if there is a posibility of getting a fertile cross from xanthina and another diploid. Very interesting. R. xanthina may be fun to work with.

I would be interested in trying a The Gift x R. xanthina cross. Have you tried crossing it with your double flowered multiflora? Is this even a worth while cross to consider?

I hope your attempts at gene doubling are successful, looks like a interesting rose (ragosa x xanthina)

Tom, I see that you’re working with Rosa carolina… I have a rose that I have a little doubt in my mind that you may help me. I think it’s R. virginiana, although for some reason I thought it could also be R. carolina. It appears that you got the white form of carolina, but are you able to recognize the leaves on my plant as R. carolina? I’ve included pics of the thorns too if it’s useful. I have to squash out my problem… and there are no sites that show clear and upclose pictures of R. virginiana or R. carolina. A lot of people say it’s virginiana, but one person thinks it’s carolina. I believe that it may be virginiana because it came from Richmond, Virginia…



This looks very much like the rose identified as R. virginiana that I was sent many years ago by a woman who lived in the Hudson Valley of NY. It suckered very freely.

Enrique, I’m not an expert, but especially not when it comes to the tetraploid North American native roses. I have a feeling that there is considerable natural hybridization going on (and probably has been going on for quite a long time) so, I’m as confused as anyone when it comes to the taxonomy of that bunch. I figure that regardless of exact ID I can still use these roses effectively in breeding programs. And they are very variable from what I’ve seen.

The only clone that I have that I now call Rosa carolina, I used to call Rosa virginiana. I’ve switched names mainly because it blooms for a second time, at the tips of its short new canes. A dichotomous key that I have somewhere, indicates that this would distinguish it from Rosa virginiana – which it mentioned would not bloom on new canes. It also has less glossy foliage than my other native clones, and is quite a bit less invasive.

One thing I can say for sure – you can’t tell the name by state of origin. I got my carolina in West Virginia and my virginiana from Maryland and Pennsylvania. Sounds like a line from a country song. ;o)

From your very nice picture, if I had to pick one or the other, I would go with virginiana. But it certainly has some leanings toward the carolina – the more restrained growth, somewhat dull foliage and flower form. The petals of my carolina are the least broad and overlapping of all my native clones and the stigma pad is also the narrowest.

Maybe what you have is a natural hybrid?


Thanks for your interest. I think xanthina is a really nice plant in its own right, but even more interesting as a parent of hybrids. And yes, I was expecting a salmon or peachy color when I crossed rugosa and xanthina – with pink overlaid over a yellowish background. What surprised me was the total inhibition of pink. As expected, the yellow is definitely much more pale than in the xanthina.

As for the double multiflora, I may have lost it to rose rosette disease. Would xanthina crossed with multiflora be worthwhile? I’d love to see it. I’ve been trying without success so far, but sometimes the “toughies” are the most interesting in the end. Hope you’ll try it too. Good luck, Tom

Thought of something else to mention…

As far as Rosa carolina repeat goes, I have Rosa rugosa X carolina which seems to repeat (since it bloomed on a totally new cane) but Rosa ‘Fragrant Cloud’ X carolina which looks like it won’t ever repeat (it hasn’t bloomed at all and is several feet tall and two years old).

This remontancy thing sure is puzzling!

I have just discovered rose hybridizing, and have already run the gamut from “Oh I want to breed a true Brown tea” to “Oh I want to breed for no disease and decent bush shape” to “Oh heck, let’s see what happens”. I think this is a typical newbie pattern…

For a long term goal, I’d like to work with (in no particular seed/pollen order)

R. wichuriana x R. californica x (a white Tea, now I’m thinking the old HT White Maman Cochet)

I’d like to use Wichuriana for its rooting abilities and for Moore’s praise of it as a breeding rose, Californica for its unusual colors in offspring, and it hasn’t been used often, and an older HT or tea for form, and hopefully some repeat. What’s the goal here? Hopefully a nice easy rooting breeding stock with some unsusual genes to play with. I suppose I’ll then breed this/these with interesting roses from there, perhaps working back to my original goal of browns and good looking shrubs. I just know I’ll end up with a lovely rose that’ll be hardy in zones 7-9 though (big smile - I’m such the Californian).

I have no idea what the the ploidy is for any of these roses, nor how to find out. Do any of you experienced hybridizers have any comments or ideas?