Clematis on the Web is a good site for information on Clematis. When a plant has a patent on it, the patented name is written in a different type font. For instance, all caps. The site is organized A-Z so you can look up the name of the plant and see how it's written. Hope this helps. Just curious, are you hoping to purchase or avoid patented plants? There is an interesting article written by Tony Advent at Plant Delights Nursery (on the web).