My Mrs Joseph Schwartz today has a matching bloom to my Duchesse de Brabant. MJS is a sport of DDB and your bloom looks very much like both of mine.

I believe it is common for either one to sport back and forth, though I have never seen a chimera such as you have.

Here is a link that might be useful: Mine have less petals

Hi Veronica
And thanks for your response!
I will have to look up "chimera" - that's a new one for me, but I love learning new words.

And I think you're right about Duchesse de Brabant. I looked on HMF and saw a picture of "White DDB" and it sure is a ringer for mine. And I looked at pic of the whole plant and could see the blooms nodding like mine.

I am so glad to have this mystery solved.

And today, all the new blooms are a really nice pink.

I hope someday you will post pictures of your MJS and DDB in your yard.

Thanks for all your help.
Susie

Susie,

I am pretty sure that you have Mrs Joseph Schwartz which IS the White Duchesse de Brabant. Your Mrs Schwartz is in her fall colors and will be much more white in spring and summer.

Here is a link that might be useful: Chimera

'Mme. Ernst Calvat' used to do that here, too.

Jeri

I followed a link here from the Antique Rose forum, and posted a response there. I'm posting it again here, with a brief addition as to why it isn't a chimera.

Chimeras result when an organism is composed of a mix of cells deriving from more than one zygote (fertilized egg). When you have a plant derived from asexual reproduction (as rose cultivars all are -- they are clones of an original plant), then every individual will thus have cells deriving from that first zygote. There may be mitotic errors (mistakes in cell copying) which can result in "sports" as seen in the third pic in the first post, but no plant grown from a cutting will contain genetic information from a different plant than the original (excepting, of course, for plants grown on a different rootstock, but in this case, there will be a delineation between one plant and the other at the graft union -- there will be no single branch or root which contains cells of both plants mixed together). Below is my response on the other thread:

It's not a chimera -- that term gets tossed around incorrectly quite often. What this is is an example of a partial reversion or sporting -- there are pictures on HelpMeFind for 'Quatre Saisons Blanc Mousseau' showing similar partial reversions even within one flower.

My thoughts on most "sports" is that they are not actually genetic mutations, but rather changes in how the genes are expressed, which is passed on via vegetative propagation (and also breeding, if the change in genetic expression is a result of methylation or a similar epigenetic phenomenon that is maintained in germ cells). The way it would work is like this -- when you see a branch "sporting" to a different flower color, or with the addition of moss, or into a climbing version, what you're seeing is genes present in the plant as a whole which are now expressed to a greater (or lesser) degree because of the arrangement of the DNA within the cells. But the actual sequence of genes remains the same.

To give a simple explanation -- think of the genes as a list of ingredients in a recipe. The level of expression would be comparable to the quantities for each ingredient in the complete recipe. When a plant "sports" according to my idea, the ingredients don't change, but the quantities do. So if the recipe originally lists "eggs" and the quantity expressed is usually "2 eggs", a "sport" would result when, for whatever reason, the cell starts putting "4 eggs" into the recipe.

This is a normal part of cell differentiation -- all our cells (except RBCs and eggs/sperm) contain all the same genes, but vary in the degree to which particular genes are expressed. This differentiation is usually fixed in most cells, with some exceptions. In plants, there is more flexibility regarding differentiation, allowing us to induce root cells to form on branches. It's probable that this "flexibility" leaves plants more prone to "sporting" than are animals.

This change can result from proteins attached to the DNA strand, or methyl-group molecules, increasing or decreasing transcription rates of certain sections of the DNA. These changes can (but not always) be transmitted to offspring produced by sexual reproduction, but are most easily maintained in plants via asexual reproduction (i.e. taking a cutting of the "sported" branch).

:-)

~Christopher

Thank you, Christopher, for the interesting post which I will now go back and reread.

Veronica

You're welcome. One thing to add -- when most people incorrectly use the term "chimera" they would actually be correct if they used the term "mosaic." They are not the same.

:-)

~Christopher