Answer: There's actually a very simple answer to what is happening with your rose. Hybrid tea roses are grafted onto vigorous root stocks. In this case, the root stock was a red rose. I also suspect your original rose bush was mislabeled - instead of yellow roses as you expected, it was a pink variety. Over the years the root stock (red) sent up new canes from below the graft union. They were not pruned away (or the grafted tea rose died down to the graft union) and because the root stock is such a vigorous grower it overtook the hybrid tea. The result is that you have both the hybrid tea (pink) and the rootstock (red) roses growing on your rose bush. If you look carefully at the base of the plant you should see a swelling on the main trunk or stem of the plant. That swelling is the site of the graft. The red roses will be coming from canes below the graft; the pink roses will be coming from growth above the graft union. If you prune away all of the growth from below the graft you'll have a pink hybrid tea. If you do not prune, the red roses will eventually overtake the pink and you'll end up with a standard rose bush with red roses rather than a hybrid tea with pink roses.
Interesting, isn't it?
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