When a rose has a split personality

Recently our local newspaper ran a picture and a story about a couple in another town that had a "rare" rose. The couple reported that they had this rose that always came up red until one winter that was particularly harsh killed the rose to the ground and the next spring the rose had red roses and pink roses on the same plant. They called the pink branch a sport and said it was rare. This led me to write this article because I think there must be a lot of people out there who don't understand how plants, especially roses are propagated.
Let me first explain that these folks do not have a rare plant. What they have is a rose that has a stem sprouting from the roots. Roses are not grown on their own root stocks. In order for roses to be mass produced they have to be grafted on to a root stock that is tougher and hardier and easier to grow than the desired rose. The root stocks are usually a wild rose that roots easier and grows faster than the scion (which is the desirable rose on top)
If the roots of the rose send up a shoot, it is a faster growing, hardier wild rose that will take over the desirable rose scion. What happened to this couple, is that when the rough winter hit and killed back the scion, the rootstock sent up a bud and so did the scion. Because the root stock is faster growing it got bigger faster than the scion stem. These people have two roses growing from the same rose. If they look at the leaves they will see they are different too. If they don't trim back the root stock branches it will eventually take over the scion and they will no longer have their desirable rose.
This same situation happens in other plants as well. Crab apples are a good example. If you plant a crab apple that has pink blossoms and all of a sudden you also have white blossoms, that means the root stock is sprouting and will take over the desirable pink blossoms in short order if you don't get rid of them.
The definition of a sport, is a branch or stem off of the top of the plant that is different than the rest of the top of the plant. This will happen especially in perennials and if it does and its a cool looking stem, it may be worth propagating. Whether you will be able to make any money off of it remains to be seen but at the very least you can grow it in your garden and have something unique.
Happy Gardening.