Fertile Triploids Breed Truer to Type?

Hypothesis: Diploid gametes from fertile triploids carry one set of chromosomes that underwent gene mixing and one set that did not, hence one quarter of the chromosomes in resulting tetraploid offspring are unaltered and one third of the chromosomes in triploid offspring are passed on as is with the implication that fertile triploids breed truer to type.

Does this hold water? If so, I’m sure it’s well documented.

My gut tells me that the chromosome that is carried unaltered from the unbalanced side is random – if so this would dilute the effect. If not, would it not enhance the effect?

Any thoughts?

And of course I’m just talking about offspring from the double chromosome side.

An example, diploid pollen from Belinda’s Dream is “halfway” like breeding directly to Tiffany. A simpler way of stating what I theorize - the tetraploid parent of a fertile triploid is more important than normal.

Woke up realizing that is doesn’t hold water. The fact that chromosome doubled infertile species crosses are highly fertile i.e Max Graf and R. kordeesi kills it.

I now believe the opposite is true - fertile triploids yield more variability - the chromosomes pair up and swap genes with the either of the two others present. I would think this variably would be really apparent with near species crosses.

Sorry for the post.


I’m now partially back on the idea. The question boils down to this. For each of the 14 sets of three chromosomes does only one pair form up and swap genetic material leaving the extra chromosome to be passed down unaltered? Otherwise it would be terribly messy - maybe the ability to do this is what makes some triploids fertile when most are not. And if that is true can one plan ahead to purposefully create a more likely fertile triploid?

As far as breeding advantages it would be a subtle effect if for each set of three it is a roll of the dice as to which two of the three pair up, but maybe its not a roll of the dice at each triplet. I wonder if Mr. Radler utilized this to his advantage in the breeding of Knock Out? It is triploid. It’s a question for smarter hybridizers than me…



Triploids vary in their nature, depending on the compatibility of their chromosomes. Of course, they also vary widely in fertility.

For example, an autotriploid has three sets of compatible chromosomes. E.g. a spontaneous triploid of a diploid species.

An autotetraploid crossed with a diploid with less compatible chromosomes would behave more like what you describe. E.g., tetraploid R. multiflora crossed with R. rugosa.

Finally, a triploid may contain chromosomes from three distinct species. E.g. ‘Basye’s Amphidiploid’ (chromosomes from R. abyssinica and R. rugosa) crossed with R. beggeriana.

Wulff (1959) described the behaviour of two fertile triploids. ‘Schneeschirm’ routinely produced tetraploid self-offspring (in Summer but not in Autumn) that closely resembled it, as you suggested.


I can’t begin to guess at an answer to your question, Baxter. I can say that until I began using fertile triploid minis, I was unable to raise crosses with R. Minutifolia and Puzzlement. The results demonstrate there has been some exchange of material between the species’ pollen and the miniatures. Ralph Moore set the stage for this kind of crosses with several of his roses, but particularly Golden Angelcalnana. 'Golden Angelcalnana' Rose I used Jim Sproul’s L56-1, which certainly behaves like a triploid, to create hybrids between it and my 1-72-1Hugonis, Minutifolia and Puzzlement. Though it hasn’t been tested, I would guess 1-72-1Hugonis is triploid from the cross and how it behaves. You can find those which have flowered on Help Me Find using the descendents tab on the pages for L56-1 and 1-72-1Hugonis. I am using Golden Angel, Golden Horizon and L56-1 this year with Xanthina, Primula, Banksiae lutescens, Basye’s Amphidiploid 86-1, Arkansana Peppermint, Californica and Stellata mirifica. Golden Horizon is triploid and fertile as evidenced by GHX86-3. 'GHX86-3' Rose There are several L56-1 X Basye’s Amphidiploid 86-3 but none have flowered yet and a few more of the L56-1 X Minutifolia and Puzzlement seedlings, also yet to flower. Most of them have demonstrated a rather wide range of results. I haven’t listed this one yet as I’m waiting to see what to expect from it. L56-1 X Minutifolia. This is one year old in a one gallon can and is only now flowering. It looks modern, but I expect it should have flowered its first year as L56Puzzle#3 did. The flowers have lasted nearly two weeks. 'L56Puzzle #3' Rose
I have been pollinating the Minutifolia hybrid with the traditional Otay Mesa Minutifolia and Pure Bea, the larger flower and foliage, white flowered form. Puzzlement has resisted every attempt and method to get it to release pollen, so I’ve ground many dried anthers and applied the dust to the L56Puzzle seedlings’ blooms, in hopes of intensifying the species traits.

Keep up the good work!

I’m reminded of the problem East (1934) with a hybrid strawberry:
“The anthers did not dehisce except rarely. Left to themselves the plants seemed to be almost completely sterile. When the anthers were scraped with a fine scalpel and the flowers were pollinated by hand, however, good fruits were obtained.”

Millardet (1894) had raised a similar hybrid, but gave it up as sterile.

Sterility of hybrids is not always due to mismatching of chromosomes.

I have collected anthers from Rosa rugosa x Rosa xanthina (Silvers) that won’t release pollen that I can detect. I was going to give up on using this one as a pollen parent but after reading the above I’ll try crushing the anthers to see if any pollen can be released.

Thank you, Karl! Puzzlement never sets seed. I’ve not pollinated it with anything yet, but left to its own devices, they simply dry up and fall off. I’ve added several of the demonstrably more fertile Teas to the mix in hopes of using them with the Banksiaes and species. I’ve long felt the infertility issues reported about them had little to do with their inability to set and carry viable seeds.

Ralph Moore often suggested crushing the dried anthers to release the pollen. He found many of the crested seedlings seemed to demand that treatment, though C04, which he felt released little pollen, releases a good deal of it in this climate where it didn’t in Visalia. I’ve found part of that problem can be the time they are given to dry. I’ve noticed several that didn’t release pollen until they had been spread on paper for two weeks and longer. And, Minutifolia and Banksiae lutescens seem to have some periods when they either don’t make pollen or aren’t inclined to release it. Some batches, treated identically to all the others, release nothing while others create “blizzards” of it when dried and shaken in the jars.

I recall reading somewhere (long, long ago) that ‘Dortmund’ releases its pollen before the flowers open.

In many cases, a given trait results from the opposing actions of multiple genes, balanced within a given environment. Anthers should split to release their pollen, but neither too early nor too late. That is, genes that strengthen the suture work against other genes that weaken it. The numbers and strengths of these gene effects are balanced against environmental conditions (heat, humidity, etc.) that also affect dehiscence.

When two species are crossed, sometimes the new combinations of genes and their modifiers produce intensified effects. Premature splitting, or non-splitting, may result – whether in the first or later generations.

Environment alone can sometimes render plants virtually sterile. For example, corn (maize) can become nearly male sterile when the anthers ripen during a hot, dry period. With no one there to crush the anthers, seed-set is low.

I wouldn’t be surprised Dortmund releases pollen early. I’ve found quite a few single to semi single roses do. Legacy and its offspring are notorious for early release. Extreme heat can also cause male sterility in a number of roses. Rosarium Uetersen was always a full puff of coral petals in the inland valley heat. So much so, I wondered how they ever used it as pollen parent as there were never any male parts. I finally saw it along the coast where temps were thirty-plus degrees lower and didn’t recognize it. Not only was it semi double, maybe three rows of petals instead of more than a hundred, but the center was exploding with stamen and anthers. The color was pastel while in the high heat, it was Peter Max neon poster paint coral. Amazing the changes something as “simple” as heat can make.

Thanks for the info. When I wrote about temperature and flower size, I speculated that heat could reduce petal-count enough to allow too-double varieties to produce some functioning stamens.
I was afraid that the heat would only influence the number of primordia - those proto-organs that become either petals or stamens, rather than the proportion of each. At least ‘Rosarium Uetersen’ behaves as I had hoped.

Now, would ‘Rosette Delizy’ and ‘Marechal Niel’ behave similarly? Or the ‘Alexander Hill Gray’ that I received this year?
Time will tell.

You’re welcome, Karl. I haven’t had sufficient flowers on Rosette Delizy to tell yet, but when I checked for pollen from Annie Laurie McDowell, Grey Pearl and Golden Angel X Soulieana, there are almost only petals with no stamen in high heat, but in cooler temps, they also produce many stamen and anthers. I’ve never checked the others you’ve mentioned. It’s common for many more double roses to produce the expected number of petals in cooler weather and become nearly single in high heat, but there are exceptions.

Exceptions are fun! Especially when we keep track of them.

The paper I cited involved only one variety, ‘Kardinal’. I would not expect the results to apply uniformly to all cultivars and species. After all, some species naturally flower in cool weather, others in heat.

I don’t have the notes handy, but as I recall, DeVries found that high nutrition favored the production of extra leaflets in clover. But in my limited experience, many years ago in Kansas, colonies of white clover growing in poor, dry soil seemed a little more inclined to produce 4-leaflets than similar colonies growing in cooler, moister spots.

It would be interesting to learn whether temperature at the time of floral initiation could influence the green “eye” in ‘Mme Hardy’. Would more heat (or less) reduce the leafiness and allow that beautiful rose to bear seed?

Yes sir, seeing whether Mme Hardy could be made fertile would be fun! Off topic, but friends found self set hips on a Fortune’s Double Yellow, which is supposedly seed sterile. Peter has removed the embryos and they seem to be growing! Fun!

I’m anxious to learn what comes of these. If they are selfs, maybe they will shed some light on the origin of this old rose.

I’m eager to see what they may result in, too, Karl. Another very interesting development…Fred Boutin, who was once the Curator of Roses at The Huntington, has discovered a rose he believes is Reine Emma des Pays-Bas. I don’t know where they dug up the information, but both Fred and Gregg Lowery (Vintage Gardens) say it is the repeat blooming sport of FDY. And, per the rose page on HMF, it is the father of General Gallieni and grandmother of Rosette Delizy!

Thanks guys. Roses are very tricky when it comes to sexual reprodction. I know a bit more now.
I read the article by Paul Barden and David Zlesak on the chromosome counts of the bracteata hybrids.
Now I see why years ago Paul was encouraging me to try Out of Yesteryear.


I don’t know if it would be of interest to you, but Ralph Moore had a Soulieana which produced repeat bloom in the first generation. Paul has mailed me three, one gallon plants of it which I wanted to be spread around. I want to retain one of them for a stock plant, and send one to a friend back east for her to get growing as a stock plant back there. The third will be available, if someone is interested.

I also would like to know where they got their information on the origin of 'Reine Emma des Pays-Bas. It is not impossible that a sport would have larger and fuller flowers, AND repeat, but are the leaves the same? Prickles?

Whatever it may be, I’d sure like to see this foundling.