I should start off by saying I haven’t got a lot of rugosa x modern seedlings to base this on because they are almost uniformly ugly and unthrifty, but with the ones I do have it almost seems like rugosa prickles and modern rose prickles are caused by different genes and that rugosa prickles are recessive to modern prickle type/coverage/etc. Every time, except once (see Rugosity, which was not a deliberate cross but an OP), I have done these types of crosses (onto ‘Scabrosa’ and R. rugosa ‘Alba’) they have turned out either smooth/thornless or with very modern looking, scattered, armory. Has anyone else noticed this? Is there anything to this? In most the rugosa x modern (in that order… I haven’t tried the rugosa as the pollen parent yet), the leaves have only had the slightest hint of rugose texture and have taken years to flower. One miniature, thornless, ‘Scabrosa’ hybrid (‘Scabrosa’ x ‘Black Jade’) has been in the ground for about 5 years now, is just 10" tall, and has never flowered but is completely thornless. Some cuttings I got from Leon Collins of his hybrid rugosa, ‘Kilmore Rose’ , also follow this pattern though the pollen parent is not known. Every time I get seedlings that end up looking like straight rugosa from deliberate crosses I can almost always guarantee they were selfs instead of successful crosses.
On a slight tangent… I think I have about 3 suckers of ‘Rugosity’ if anyone in Australia would like one. PM me if interested.
That’s a good question Simon, so I checked a few of my Hybrid Rugosas. On Moores Striped Rugosa the thorns are as you described, fewer and more modern looking. Possibly because it’s a triploid with two sets of chromosomes from it’s mini seed parent and one set from the Rugosa pollen paernt. On Topaz Jewel the thorns were hooked with a broad base like a moden but very numerous like a Rugosa. Topaz Jewel is a diploid so it looks like that in this case the genes from each parent are expressing themselves equally.
I have a tetraploid rugosa (verified by pollen grain measurement) that I grew from seed. I have numerous OP seedlings from it as well as seedlings from a cross of it by Frontenac. Based on the color and texture of the leaves of the seedlings, I’m very sure they are hybrids. The seedlings are still pretty small but I would say that almost without exception the thorns resemble the Rugosa parent. So in this case the rugosa genes are dominant at least so far.
It’s interesting, however, that in ‘Frontenac’ rugosa features in its pedigree through ‘Max Graf’ a few generations back. Is it possible that a latently carried rugosa feature is then coming back out in your seedlings as a recessive gene might be expected to?
I guess anything is possible when you’re dealing with genetics. While Frontenac doesn’t have the prickly armament of R.rugosa it has does have several roses in its lineage that are quit prickly from both of its parents and it’s possible that they could have been passed on to my seedlings. I have 22 seedlings from that cross and they are all prickly. If the trait were recessive all the seedlings would have to have gotten two copies of that trait from Frontenac, which isn’t likely since we know Frontenac isn’t homozygous for prickliness becasue it’s not prickly.
I looked at several of my roses that are hybrids of a prickly species or near species with a modern rose. And I see a gamut of armaments. Red Dawn x Suzanne is nearly thornless while Easy Going x Suzanne is very prickly. I have two R.arkansana OP hybrids where the armament is midway between R.arkansana and the modern. The prickles have the modern shape but there are more of them and they are smaller than a typical modern thorn.
You may be right about more than one locus involved with armament. I have a thornless R.blanda that I crossed with Marie Pavie and with the Rugosa “Showy Paventâ€. Marie Pavis is for the most part thornless (it does grow some canes with thorns) and my Marie Pavie x R.blanda cross is thornless. The Showy Pavement x R. blanda cross is prickly like Showy Pavement. I crossed these together figuring that 50% of the seedlings would be thornless based on thornlessness being recessive to prickly and only one locus being involved. Well to my surprise all of the seedlings are prickly. So either only the eggs with the rugosa armament allele were fertileized or something else is going on.
The prickles often change, but the new growth and flower buds get really fuzzy, like Bracteatas do. I can’t work with Muriel. The fuzz makes me break out and itch like okra and fiberglass. Linda Campbell isn’t as bad, but modern Rugosa hybrids frequently have that fuzz that makes dealing with them rather unpleasant to me. Mosses get sticky from the resinous secretions, but at least they don’t make me feel as though I’ve been cleaning hips or playing in insulation.
Kim I know how you feel. Cleaning out hips make me break out too. That why I pretty much try to do as much as I can at one sitting. Latex gloves help a little bit, but I still manage to get it on my arms some how. After I am done I always have to take a shower. It is one of my least enjoyable task. The same goes for pruning rugosas and especially dealling with something like hollyhocks.
As for observations on rugosa hybrids. I have no real rugosa x moderns. I tried the rugosas many as pollen parents until this year and they have failed mostly with modern roses. Maybe I will get more this year as female parents. But I do have some hybrids with some species and the hybrid musk Cornelia. The rugosas used in these crosses are Hansa, Anne Endt, and Scabrosa.
Rugosa x R. woodsii- all the plants 20 or so are extremely thorny with straight thorns covering most of the stem.
R. foliolosa x R. rugosa- These 15 plants or so are divided between 3 groups. 1. the largest group has alot of thorns like a typical rugosa. 2. the next group does not have a many thorns as a typical rugosa but they are nowhere near thorn less. 3. the last group containing only 3 plants are all from the pollen parent Anne Endt. These 3 plants contain very few thorns and most of the ones they do have are on the underside of the leaves and not the stems. All three groups seem to have both straight and curved thorns. But mostly straight.
Cornelia x Rugosa. These pretty much follow the patern that Simon has noticed. Only 2 out of 10 are completley thornless. These two look nothing like a rugosa.
None of these hybrids have bloomed yet. This is their second year of growth. So maybe later this year or more likely next year.
Picked up Pink Grootendorst this year, the tag said profuse recurrent bloom and it has a lot of prickles but not nearly as big and nasty as some of the Rugosas I seen this year and it’s a diploid.
It also seems to be that rugosa thorns and more traditional modern thorns are made in different ways. It seems that the traditional hooked modern-type thorn is made on something like a shield that can be broken off cleanly. Rugosa thorns seem to be continuous with a layer of tissue that isn’t present on these more modern roses and you can’t actually break them off in the same way as you can with their modern counterparts. So I was thinking maybe they were controlled by factors not necessarily even related to thorning. The tissue on the stems of rugosa stems, as Kim says, seems to have a fuzzy coating which gives me a reaction like picking peaches did as a kid. It also seems to be less woody on the outside and more pithy and that the prickles seem to orginate from this layer instead. The prickles on ‘Belle Poitevine’ were deceptive as they have the appearance of being menacing but when I touched them they pretty much folded like paper and weren’t very scary at all. This is why I decided to use ‘Belle Poitevine’ last season. It would have worked too if some critter hadn’t decided they needed the hips more than I do! I have never seen the rugose prickling form and arrangement on the more smooth, shiny, and hard stem except on ‘Ann Endt’ and even then it’s only on the watershoots. The mini that I mentioned earlier (‘Scabrosa’ x ‘Black Jade’) started forming little straight prickles in a rugosa form and arrangement but because they were formed on hard, shiny, smooth, stems with that shield-like attachment they all break off early giving the impression thta it is completely smooth. The gentle action of the wind rubbing stems together and against foliage was enough to rub them off. In fact, I noticed in its first year that if I was to just run my fingers up the stems gently the prickles it did have, which wasn’t many, simply brushed away cleanly. Does this kind of observation run true with anyone else?