Question: I planted a Hybrid Tea rose, but now I have a plant that looks like a blackberry bush. Its flowers are also very much like a blackberry. Why would a rose mutate like that?
Answer: What you have is the rootstock of the original rose. It hasn’t mutated at all, but the top must have died out. If there is any of the top growth still intact, cut out all of the rogue shoots from the rootstock. Otherwise, just dig it out and replant with a new rose plant.