Flat and ribbon-like?

If so, It's likely Fasciation, which I'm told can be triggered in otherwise normal roses by weird weather fluctuations.

Gaia knows, we have had our share of weird weather fluctuations this year.

Here's what Wikipedia says of it:
"Fasciation (or cresting) is a condition of plant growth in which the apical meristem, normally concentrated around a single point, producing approximately cylindrical tissue, becomes elongated perpendicularly to the direction of growth, producing flattened, ribbon-like, crested, or elaborately contorted tissue. The phenomenon may occur in the stem, root, fruit, or flower head.
Fasciation can be caused by a mutation in the meristematic cells, bacterial infection, mite or insect attack, or chemical or mechanical damage. Some plants may inherit the trait.
Fasciation is rare overall, but has been observed in at least a hundred different plant species, including members of Aloe, Celosia, Delphinium, Digitalis, Euphorbia, Forsythia, Primula, Acer, Prunus, Cannabis and many genera of Cactaceae (cactus) and Salix. Cresting results in undulating folds instead of the typical "arms" found on mature Saguaro cactus.[1] Some varieties of Celosia are raised especially for their dependably fasciated flower heads, for which they are called "cockscomb"."

Jeri in Coastal Ventura Co., SoCal

Weird weather, amen. This is intriguing. And yes, there does seem to be a cockade of stems at the top.

Very interesting. I can't remember what plant I saw it on, but I recently saw flat atypical canes while pruning. Lord knows we've have enough weird weather during the last year. I'll keep my eyes open. Jeri, thanks for the information!
Melissa

aha, we see a lot of this on tropolaeum tricolour and a tall veronica called, confusingly, Fascination (which, I must assume, is some kind of pun as it gets these flattened stems every year). I have certainly seen it on an old white rambler at my horticultural college (up till then, I didn't think roses were affected). I think there is a genetic disposition in some plants - a number of heritage tomatoes get a sort of proliferation (which is a similar rampant growth) from cactiflora genes - although, let me make it clear before better educated GW members respond, this is all based on unscientific observation on my part and may have no veracity whatsoever. Interesting though, hey?

I've had this happen once before too. I just removed the funny cane and the plant continued to grow normally from there on out. It's like instead of seperating into two or more canes somehow they just fused themselves together to form the one thick flat, ribbon like cane.

I've had lilies fasciate. They produce amazing amounts of bloom when that happens. I don't know if the same is true for roses.

Rosefolly