Gina, that looks like a pretty big Saffron plant. Have you had it long? Did you get it from HVH? I can't recall ever grafting a Saffron but may have done so many years ago - say prior to 2005.
In any case, if it is a grafted plant, people usually cut off any "suckers" that grow from the root stock. Flowers from standard root stock plants are small but sort of interesting. The standard root stocks used are Pride of Hankins and Albo lacinatus. You can view photos of them in the Hibiscus Gallery pages of the HVH web site.
If you really want to see the "different" stem bloom then do not prune it at all. Just wait and sooner or later it will bloom. Eventually the root stock will compete with the main plant so it is not usually a good idea to let root stock sucker branches grow. As Mike said, cutting it all the way back to where it joins the main stem is the best strategy in this case.
The other possibilities are that there was a second cutting of another variety planted in the same pot with the Saffron and it is just now getting enough strength to grow and reveal itself to you. Or, this stem is just growing differently due to environmental factors and will bloom with normal Saffron flowers and most likely any leaf differences will disappear over time.
This is a bit of a mystery since we don't graft Saffron normally.
Charlie
I was reading all this with very little interest until I came to the last line about never grafting Safron, haha now Gina you are just going to have to leave it to see what comes, could be something wow!!!.
