I had an interesting experience with Veilchenblau, a smooth or relatively smooth once blooming rambler. Abouat 4 years ago, I made my usual October trek up to a nearby rosarians garden to take cuttings. I was sick and tired of handling roses and getting thorns and untimately warts on my hands (due to the breaks in the skin barrier allowing the virus to enter). I was seeking out thornless roses and mentioned Veilchenblau specifically. My rosarian colleguee mentioned he had moved his earlier that year and must have left some roots which had since sprouted and I could take those small plants if I wished. When we went to the spot, there were two rose plants growing about 2 feet high. The canes were very thorny. I said, this can’t be V and he said, it must be since I had no other rose in that spot. So, I dug them up and like a good doubting Thomas, I asked could I see the specimen of V which he had moved. It was smoothcaned. For “insurance” I asked if I could take some cuttings of the smooth caned V which I labelled V2. The thorny specimens were labelled V1 which I also took some cuttings from. About a year later, all cuttings had taken and grown and were growing lustily. V1 was thorny and V2 was smooth. I had a back fence which bordered a neighbor’s woods and decided to plant all the thorny V1 plants along the fence since he never went there and if they went over the fence, the thorny canes would be no problem. They grew and grew and bloomed and were absolutely lovely. V1 was truly Veilchenblau though loaded with prickles. The following year, I noticed several of the new canes were growing and were as smooth as could be, the plant now having both smooth and prickled canes. As of this year, for the most part, all the canes are entirely smooth or only have an occasional prickle as the older thorny canes died off. Obviously, the remaining portions of the original plant in the ground were stressed which either turned something on or something off which resulted in canes with abundant prickles. It wasn’t a factor of youth since the cuttings from V2 were smooth to begin with and remained that way as they rooted and grew into new plants. Enrique and others have mentioned this phenomenon before as did Basye. Stress conditions of one sort or another create physiological changes which induce or reduce prickle formation. What are those environmental changes and what gets turned on or off to result in more or less prickles.? An interesting experience.
Jim