Several years ago my white climbing rose suddenly produced a blossom that was half white and half pink. Today I found eight roses on one stem...five white and three bright pink. Any idea what causes this?

Do you know the name of your rose? It's really beautiful! Roses can sometimes have a small genetic mutation that will cause the color to be different. That is known as a sport. Any rose can have a sport at any time and some roses are even prone to doing it. There are many things that can cause it to happen. Weird or sudden weather changes, too much fertilizer, any kind of change to the plants growing conditions. Sports are not always stable. That means they may happen once and then never again. If a sport is stable that cane will continue to produce the other colored blooms. Tie a ribbon to that cane and keep an eye on it to see what it does the next time it blooms. Also if a rose was a sport from another rose it can occasionally revert back to the original rose. Knowing the name of the rose might help us to determine which you have.

The climber is about 20 years old, and no longer has a tag on it, so I'm not sure of it's name. This has happened twice in 20 years, and the cane it is on now is not an old one. It is startlingly beautiful to look out and see bright pink roses on my white climber! The first one was eleven years ago!

The interesting thing is that not all the roses on that stem are pink. five of the eight are the original white. And I have never seen a rose that was half one color and half another. One of the white ones has one pink petal. The lighting is making the white roses look more yellow than they actually are.

Then this is probably NOT a stable sport. What ever genetic mutation occurred happened in the bud formation and not in the cane itself. Think back to 6 or 8 weeks ago when these buds would have begun to form. Were there any strange weather conditions? Whatever the case they are lovely surprises to enjoy! They are perfectly natural and will not harm the rose in any way.

I sent the pictures to my son, who is a PhD in microbiology and genetics at Yale. He said it is a chimera. I found another picture of a half red, half white rose on google when looking up "chimera genetics" Also pictures of animals, particularly cats with the genetic mutation. Interesting. He said not to cut back the cane and watch to see if it happens again on that cane. I'm going to tag the cane so I can keep track of it.

It is but you three are talking about the same thing. A chimera is a mutation, a sport and is common in roses and variegated plants. A chimera can also occur on leaves or in fruit. Usually, the plant reverts back to normal but Mother Nature is the one who decides. A related term is reversion and it works "backwards" from what you are now seeing. Reversion occurs when a cultivar known for a particular bloom/leaf shape, color, etc "reverts" back to a different/previous form found in the plant's parentage. It is often used to describe a variegated shrub that produces non-variegated shoots similar or identical to the ones that its parents produced before. I have had a reversion with a Camellia Japonica Eleanor McCown too. Its blooms are typically white with pink stripes. One branch then started producing completely white or completely pink blooms, like its parents do.

In animals a chimera is the result of two embryos that fuse together at a very early stage of development - no mutations involved.

(My reply vanished, so here it is again.)
The yellow and pink rose on the same bush is probably "Lindy Lane's Yellow", a found/mystery rose that two or three of my rosarian friends grow in their gardens.

The white and red rose on the same bush is probably 'Smith's Parish', also known as 'Fortunes Five-colored Rose' from the 1850s. That second name really should have been--to be more accurate--Five-PATTERNED Rose, Sometimes half the rose is red, the other half white; sometimes the white rose has just one or two petals in red, sometimes it shows a few red stripes or markings.
Darrell

A fascinating discussion! Thank you all for sharing! I wish I had a rose like that!

I am hoping to start a rose bush from cuttings this year. I have viewed a few youtube videos and love their romantic beauty!

schrammd said:(My reply vanished, so here it is again.)
The yellow and pink rose on the same bush is probably "Lindy Lane's Yellow", a found/mystery rose that two or three of my rosarian friends grow in their gardens.

The white and red rose on the same bush is probably 'Smith's Parish', also known as 'Fortunes Five-colored Rose' from the 1850s. That second name really should have been--to be more accurate--Five-PATTERNED Rose, Sometimes half the rose is red, the other half white; sometimes the white rose has just one or two petals in red, sometimes it shows a few red stripes or markings.
Darrell

Both these are from the SAME bush, eleven years apart...a white climber. The rest of the roses on the bush are white. Only this one cane has the yellow and pink roses. And the cane is not a sucker because another branch off the same main cane has plain white roses.