Rosa californica

Was reading ‘The complete Book of Roses’ by Gerd Krussmann and came across Rosa californica info concerning natural variations. I remember JimT posting somewhere of the purple/red version and this book states 3 variations other than the species. One is ‘Ardens’ which is similar and discovered in the 1930s. Another is ‘Nana’ which is dwarf and discovered in 1914. And the last is ‘Plena’ which most of us have read about and its relation to the species is questioned a lot. I bet there are more. My sample that I rooted and am growing is identical to the text description except for being a paler pink. ‘Nana’ sounds interesting to work with.

‘Plena’ is diploid while R. californica is tetraploid. A DNA analysis in Japan a couple of years ago showed that there is no relation between ‘Plena’ and R. californica.

There is a lot of variation in the species R. californica, just as there is with all North American species. The local variety blooms continuously, while other varieties just bloom once. There is a plant with semi-double flowers in the area. Once I saw a mossy sport on a plant near my house. Unfortunately, I wasn’t able to propagate it. In this area, the color varies from very light pink to medium pink. I remember seeing a post of a photo of a darker one a while back (I think it was on the RC forum), but it wasn’t me who posted it. As I recall, it was posted by someone in northern California, and is probably similar to the R. californica ‘Dark Pink’ available from Vintage Gardens. I have not seen ‘Ardens’, but I believe that it is another dark colored variety.

I have not seen ‘Nana’. I suspect that it might actually be the dwarf species R. spithamea which grows in the same area R. californica.

So far, when crossing R. californica with modern hybrids, I’ve gotten no seedlings from R. californica as the seed parent, and only a few seedlings from it as the pollen parent. Perhaps varieties from other areas will be more fertile. On the other hand, the local variety of R. spithamea is fairly fertile both ways when crossed with modern hybrids.

Jim, have you tried crossing R. Californica with diploids?

Jim, I’ll tell you if my Rosa californica x Shadow Dancer produces any seeds. 2 seed pods still swelling now so we will see. I was walking in a local park with my friend and we noticed so many interbreeding. One looked very foliosa like. He grabbed seed pods from anything unusual and there were a lot of non-textbook examples of local species.

Judith, I have crossed R. californica with several diploids, but haven’t gotten any hips from those crosses. I’ve only gotten seedlings when I’ve crossed it with tetraploids. I’ve had better results crossing it with tetraploid species than tetraploid hybrids.

Jadae, I will be very interested to hear how your cross turns out.

Jim, I harvested 20 seeds from 2 hips today. Hopefully they’ll germinate in the spring.

Congratulations, Jadae! I hope they germinate well for you. I’ve had five germinations from Armada X R. californica in the last week. There was only one germination from that cross last Spring. I put the seeds back in the fridge in June, took them out a couple of weeks ago, and now they’re germinating. Armada seeds generally germinate well with little or no chilling, so I’m surprised that these apparently needed two chilling cycles.

Thanks Jim. Armada sounds fun, too. I have thought about trying Octavia Hill (Armada descendant) in the garden. I originally planned for Dreamcatcher for my cross but after 3 tries it wasnt producing beans for pollen so I went to Shadow Dancer which produced a ton. Shadow Dancer seems to be the best pollen producer of my striped roses.

Jim, I’ve looked at a few articles by Japanese phylogenetic researchers. I finally found the article that probably shows no R. californica in R. californica ‘Plena.’ There was no discussion of that result specifically. The odd result is shown in a Phylogenetic tree showing ‘Plena’ closely allied with R. canina, even more closely that other members of the Section Caninae.

Have you read the fascinating 2007 study by Bruneau, Joly et al. reporting that they suspect “contaminated botanical garden samples” as responsible for some odd reports on R. californica? They cite two results by Matsumoto and one by Wissemann. It could have been a rootstock problem.

This is what I have on R. californica ‘Plena.’ British references like Hilliers note that Rosa nutkana ‘Plena’ and Rosa californica ‘Plena’ are the same, possibly confused in commerce. Beales’ website confirms this. Bean says that Rehder added the name Rosa california forma plena on the basis of the illustration in Willmott which shows at least a semi-double bloom. I have not read the Journal of the Arnold Arboretum yet. I found a reference in Arnold’s cultivated herbarium database for a garden specimen collected in 1939 labeled Rosa californica var. plena. In any event, Bean says the plant was introduced to the UK from a plant from Bobbink & Atkins. My 1937 Bobbink & Atkins catalog has no ‘Plena’.


I have never once believed that R. californica ‘Plena’ was in any way related to any of the wild forms of Rosa californica. Also, I do wonder what kind of “Rosa californica” LeGrice used and studied.

So we can draw a stripe through ‘Rosa california plena’?

Is it easy to do a DNA test with Rosa california plena and Rosa nutkana ‘plena’ and see if it’s the same?

R. californica ‘Plena’ has very distinctive red wood. It’s quite pretty. It would be nice to have the ploidy confirmed of specific, identified cultivars.

I found a PhD thesis from the University of Ghent containing a flow cytometry study showing R. californica ‘Plena’ is tetraploid. The author noted that result was is in conflict with an earlier result that showed it was diploid but didn’t list his accessions. I would include both in the spreadsheet. It’s all just data at this point.