Rose Of Sharon shrub has small amount of pure white flowers

I've got a rose of Sharon shrub that is well over 30 years old. Most of the shrub has pink flowers with maroon-red in the throat of the flower, a typical rose of Sharon. But right in the middle of the shrub, a large branch always gets pure white flowers year after year, no red color in the middle pure white!

At first I thought I had 2 plants that grew so close and intertwined, but they share one stem that just branched off after so many years.

Could it be a grafted branch that just didn't flourish like the branches that produced pink flowers, or could it be genetic where a single branch produced mutants that lack pigment, the branch has never been pruned or removed.

I saved seeds and most come out pink, but some do produce the pure white flowers.

I tend to suspect a grafted plant since I think it's reasonably common to graft ROS. But it could be a sport too. Seeing what color you get in seedlings doesn't really help solve the mystery of the white branch since many ROS's are hybrids and wouldn't come true from seed.

Here is a photo of the shrub.

Sorry, can't tell anything from that pic (since you aren't showing the base, from this angle it looks like the white could be a separate plant from the pink). If you want to check if it's grafted, you'll need to do some closer examination down closer to the base of the shrub.

First let’s examine the possibility that this is a spontaneous stem mutation. The bulk of the plant has pink flowers with red-eyes both of which are genetically dominate traits in Hibiscus syriacus. The white flowers are pure white with no red-eye which are two genetically recessive traits. At a minimum four recessive mutations on two different pairs of chromosomes would have to occur at the same time, in the one cell which gave raise to the stem, for this to be a stem mutation. This is a statistical impossibility and the white flowers have to be the result of human intervention.

What has not as yet been established is that the Hibiscus syriacus a graft or two plants growing side-by-side. From what I can see in the photograph this appears to be graft but I am not completely confident of that. Because Hibiscus syriacus stems don’t dieback for the winter, it has been popular to offer multi-colored Hibiscus syriacus grafts for many years with the most popular being tricolors, in a red, white and blue conformation. As true reds have still not been achieved, I suspect that this Hibiscus started out as a red, white and blue graft, with pink being a stand in for red. At some point the blue graft failed and pink flower, most likely being the root stock, became dominant, resulting in the plant we see today. If you Google “Hibiscus syriacus tricolor” you will see what I am talking about.

In another post at http://davesgarden.com/community/forums/t/1282320/#Post_9300006 it was suggested that this plant may be over 30 years old putting its age back to the late 1970’s or earlier. If that age is correct, there is a very good possibility that this white flower, which sets seeds, is a Hibiscus syriacus 'William R. Smith' which has disappeared from the hobby in the United States but is still available in Europe. Grafting is a time consuming process and given the expense involved, you might as well use the best grafting material available, which would have been Hibiscus syriacus 'William R. Smith' in the 1970’s.

I would very much like to know more about the history of this Hibiscus and how it came to be in its current location. I would also like to suggest that the white stem be cloned and get the suspected Hibiscus syriacus 'William R. Smith' growing back on is own roots, assuming there is sufficient wood to do so.

Mike

This message was edited Oct 10, 2012 9:28 AM

When we moved to this house the plant was already here, that was back in the mid 80s, there were more of these plants, some the whole shrub pure white and yes there used to be lavender too!

The seeds from this white part produce pure white flowers from seed, identical to parent. which is amazing no red center! I have plenty of seeds from it I could send you that I just seperated from the seed pods. You could send me a self addresses envelope I'd be happy to send you right away, if your correct about the cultivar I'd want you to have some to keep it alive for us common gardeners and for your research.

Another neighbor behind me had a whole row of mixed rose of Sharon, once in a while a white flower developed red stripes like a candy cane, the seeds from it failed to germinate, and last year every shrub was removed! Seedlings from them are still in my yard and I've seen all sorts of crazy mutations resulting. It's a rose of Sharon gold mine here but nobody ever saw a passion for them like me and all these years my seedlings and seeds were only for my pleasure nobody to share with.

Here are photos of the white flower, pictures are a bit dark and fyi the flowers are usually a bit more larger this is one of the last flowers of the season. Also a photo of the bottom of the plant, seems like it might be a graft.

I have noticed that white Hibiscus syriacus bloom late into the fall. I drive by a Hibiscus syriacus White Chiffon every day and it is still in bloom as of October 12, 2012.

You should really try to get your white Hibiscus syriacus growing back on its own roots next spring. A graft of this type is always at risk of failing at the graft-union. As I speculated, this Hibiscus was most likely a tricolor where the blue graft failed at sometime in the past. While this white Hibiscus syriacus will breed true to color, seedlings will not be an exact copy of the parent. You need to clone, to get an exact copy.

When searching for heirloom Hibiscus syriacus, old tricolors (i.e. before 1970) may be be likely sources of candidates because the best graft material, available at the time, would have been used. I believe that this is a Hibiscus syriacus ‘William R. Smith’ but we may not be able to prove it with 100% confidence.

Mike

I can try grafting in the spring, what's the best method?

Also some seedlings from it have smaller petals coming from the center, none of these flowers have visible petals in the center, so I assume its a dormant trait only reveled when seeds from these flowers are grown? Perhaps that is how the double flowered variety first began, and over time extra petaled individuals were bred to grow larger, fuller petals until the center was almost completely covered. Like I said if you want free seeds let me know you can have some to grow and experiment with.

I was not thinking about anything as complex as grafting. If you take cutting from Hibiscus syriacus next spring you should be able to root the cuttings, creating clones of the parent plant. If you are new to rooting Hibiscus, I would suggest that you don’t experiment on the bicolor Hibiscus first, use a Hibiscus with more wood first. There is a good video on YouTube on how to do this.

A Simple Way To Root Plants From Cuttings
http://www.youtube.com/watch?v=WyXSNzywqvw

Last year I cloned a number of Hibiscus syriacus, including one plant which may be a Hibiscus syriacus 'William R. Smith' using cuttings provided by a friend of a friend. Two of the cuttings rooted successfully and one plant flowered (see attached photo), which I self pollinate resulting in a growing seed pod which should be ready in a few weeks. It is definitely not Hibiscus syriacus Diana but I can’t be sure that it is ‘William R. Smith’ either. The other clones are wild whites with red-eyes Hibiscus syriacus which the NJ DOT has been unsuccessfully trying to exterminate for a number of decades now along a state highway near me. I have designated these Hibiscus syriacus ‘Delawanna’ for the location where I collected them.

Mike