'Schneezwerg' was tested for cold hardiness along with several other Rugosa hybrids by Dr. Felicitas Svejda for her breeding programs of this type of rose. It was the best in this respect. It's definitely cold hardy to Zone 3a and also does well in Zone 2.
This cultivar also has the best repeat bloom of any Rugosa hybrid, flowering late into the fall. It's progeny, 'Jens Munk', also repeats very well.
Interestingly, the hips of 'Schneezwerg' also mature the quickest of any Rugosa hybrid. It's likely the result of the other species besides Rosa rugosa in its parentage, which hasn't been definitely determined yet. I lean towards Rosa laxa or Rosa fedtschenkoana. It's not likely Rosa beggeriana as sometimes stated in the literature.
Paul, did you mean to say that it's not likely R. bracteata as sometimes stated in the literature? Your information on the main page entry about the R. beggeriana parentage coming from Skinner seems reasonable, unless there is some other reason to doubt it. Certainly it would be less likely to come out diploid with R. laxa or R. fedtschenkoana (both tetraploids) as parents. Other diploids like R. beggeriana or 'Ross Rambler' (whatever its species affinity may be) would seem more likely.
'Schneezwerg' definitely doesn't have Rosa bracteata as a parent. Rosa bracteata is a very tender species and therefore couldn't contribute to the excellent cold hardiness (Zone 3) of 'Schneezwerg'.
The information I provided that is on the main page - I'd like to have the last sentence eliminated because I no longer agree with Mr. Skinner that 'Schneezwerg' has Rosa beggeriana as a parent. According to Peter Harris, Mr. Skinner (at least in one point of his life) incorrectly identified Rosa laxa as R. beggeriana. Therefore, he should have said that 'Schneezwerg' had Rosa laxa as a parent.
Apparently there are Rosa laxa genotypes that are diploids.
'Ross Rambler' is a selection of Rosa laxa so it's nothing special, although at the time it was discovered at the Indian Head (Saskatchewan) Forestry Station in 1918 it was somewhat of a sensation because of its great height (24 feet). This selection appears to have been a diploid. Note: Some roses if grown in a shady location can grow quite tall because they reach for the light. I've seen a Rosa laxa seedling doing this.
I won't rule out Rosa laxa as a parent of 'Schneezwerg', but I think it's more likely Rosa fedtschenkoana is. Rosa fedtschenkona has smaller leaflets than Rosa laxa and therefore this could account for 'Schneezwerg' having finer foliage than Rosa rugosa or many of its hybrids. It's a very unusual Rugosa hybrid in this respect and still maintaining rugose foliage. Furthermore, Rosa laxa selections often flower just once, whereas Rosa fedtschenkoana can flower into late summer.
Rosa fedtschenkoana, of course, has a long breeding history in Europe since it is in the pedigree of Damask roses. There is no historical record of Rosa laxa being used in European rose breeding programs that I'm aware of. This doesn't absolutely prove that Rosa laxa isn't a parent of 'Schneezerg', but I like to think it's a factor why Rosa fedtshenkoana is.
By the way, note the shape of 'Schneezwerg' hips. It's what would be expected when a rose species (eg., Rosa rugosa) having globose hips is crossed with a species (Rosa laxa, R. fedtshenkoana) having pyriform shaped hips. Rosa beggeriana, having very small globose hips, couldn't contribute to the distinct shape of 'Schneezwerg' hips.
Thanks for clarifying that, Paul! I agree that R. bracteata is well and truly done as a possible parent in this case; I was mainly trying to reconcile your more recent comment with the one that was posted on the first page of the entry for 'Schneezwerg'.
I really don't feel that we have a good handle on the taxonomy and identification of the Central Asian species allied to R. laxa, especially in cultivation, and I have a strong suspicion that there may be more going on than simply different ploidy series within a single, highly variable species. At the very least, I would expect that we are dealing with taxonomically distinct subspecies, and probably more likely two or more "good" species between the diploids and tetraploids. If there are reported diploid forms of R. fedtschenkoana, I've never heard of them--I've only ever understood that species to be tetraploid, and most R. laxa chromosome counts I've seen tend to list that species as tetraploid as well. I'm very reluctant to consider 'Ross Rambler' to be just a selection of R. laxa until the variation within the species has been much better characterized, because it seems a lot like it could well belong to a separate species to me (I also agree that the extraordinary height reported for it at the time of selection was probably not significant in any way.) I'm sure you know that 'Ross Rambler' also flowers repeatedly (if sporadically) through the season.
Since 'Schneezwerg' is a diploid, it is almost impossible to believe that either of its parents could have been tetraploid; if that were the case, then it should almost certainly turned out to be triploid instead. That tends to rule out R. fedtschenkoana and most typical (tetraploid) forms of R. laxa as possible parents, I think. It's only so useful to guess what species material might have been available to its raiser, since there would have been a fair number of species introduced to European gardens and available at the time it was bred. Some of them may have been mislabeled, as has always been the case in horticulture, so even parentage reported in good faith sometimes has to be taken with a grain of salt.
The shape of the hips (and receptacles) does show evidence of some hybridization, of course, although I don't know that the specific shape is necessarily so inconsistent with R. beggeriana parentage. That isn't to say that R. beggeriana absolutely must have been the other parent, but the sometimes relatively high number of flowers per corymbose inflorescence also may point in that direction. I'm inclined to accept that as the likeliest species parent with R. rugosa, with possibly a diploid 'Ross Rambler'-like selection as another contender, but it would be very useful to see some genetic testing done with this variety and its assorted possible parent species.
I really don't feel that we have a good handle on the taxonomy and identification of the Central Asian species allied to Rosa laxa,..."
Totally agree. We know very little in this respect.
I note apparently there is a hexaploid (6x) Rosa fedtschenkoana, so perhaps there are also diploid populations. The Rosa fedtschenkoana we have available to us likely comes from a very limited number of populations and perhaps also from a small number of geographical regions. Especially from this species, I would like to see more botanizing done.
It's accepted that 'Ross Rambler' is a Rosa laxa seedling.
I also would love to see the results of the genetic testing of 'Schneezwerg'.
"Furthermore, this species is once blooming and therefore if combined with Rosa rugosa the progeny would also likely only flower once."
Someone should tell that to the Bracteata growing here.
It's 100% not a parent of Schneezwerg, other than being white flowered and smaller leaflets there's no resemblance (bracteata has huge flowers, rugosa's typically aren't small either...Schneezweg's flowers are smaller than typical rugosa).
I didn't respond directly to that comment myself since it's a moot point in this case, but Rosa bracteata is fully repeat-blooming here in the eastern U.S., too. I would presume that more or less continuous sporadic flowering is the natural behavior of the species. Oddly enough, though, the Flora of China only gives May to July for the flowering period. That almost has to be a mistake. In the Flora of North America treatment it is listed as May to October.
The flower is moderately fragrant (not mentioned on the main page). The crushed leaves, I'm not detecting anything reminiscent of rubiginosa or any particular scent other than "green"....do plan to use this quite a bit in breeding being one of the few rugosa's that's shown ability to produce fertile offspring with (some) china/tea....working on removing the delayed bloom.
I'm not so impressed with the plant itself so far, can't place my finger on why though, probably just needs to grow another season or two.
Hi! My Dictionary of Rose Cultivars lists Schneezwerg (aka Snowdwarf) as "probably R.rugosa x a white Polyantha. Pure white, semidouble, flat, 6 cm./2.4 in. across, yellow center, several together, floriferous, recurrent, small red hips in the autumn, growth vigorous, foliage like R.rugosa, wrinkles, but smaller."
Supposedly, beggeriana has a rubiginosa foliage fragrance but is allied more closely to fedtschenkoana because it is slighly remontant. I can't wait to mix rubiginosa and fedtschenkoana together via Quatre Saisons Blanc Mousseaux x AppleJack to get a remontant super fragrant entire plant!
