I'm a complete clematis murderer but since you didn't get an answer, I did some research and found out that it likely will not be true to form. I imagine if you only grow one type of clematis it might come true. I got the following article from the International Clematis Society, link to full site below.

"Germinating Clematis from Seeds
Clematis seeds may take up to three years to germinate, but you should get some germination in about six months to a year. Collect ripe seed in the fall and plant in sterile seed starting mix, covering seeds with a thin layer of sand. Place the container into a zip lock polyethylene bag and place it outside in a shady spot (or a refrigerator) for several months during the winter so that they go through several freeze/thaw cycles.

Then place the covered container in a warm location out of direct sunlight and wait for your first seedling. As the seeds germinate, the small plants should be pricked out of the germinating container and planted into a small pot using a sterile soiless mix. Be very careful as the root will be a single long root in the beginning. As it grows larger it will need a larger pot, fertilizer and constant moisture. When the plant has three sets of leaves, pinch out the growing tip to promote branching.

Seeds collected from hybrid clematis will usually not breed true to the parent so you might create a new and exciting cultivar that may be named after yourself or a loved one. The chances of getting a new winner are about one in 200, but acceptable smaller flowers of little commercial value will result. They make great gifts to fellow gardeners if you get too many.

Your seedling will take at least a year to offer its first bloom and another three years to become a mature plant. I usually wait until it blooms before planting it out in the garden. A greenhouse helps. It is a labor of love! Good luck!

Bill Bird, USA."

North53, I think it would be ok to sell them at a sale as long as you label them as "open pollinated".

Here is a link that might be useful: International Clematis Society

Thanks Northspruce, I'll label them 'open pollinated" as you suggested. Of course, then they'll want an explanation of what that means! At any rate, they'll get some kind of vine.

You're welcome! By the way, I'm sick with jealousy that you have clematis seedlings - mine didn't sprout! :0) Maybe if I leave them 3 years like the article says...

I also WS'd some clematis seed from Patrick Studio. So far none have germinated. The seedlings from the bluebird just popped up this year in my perennial border, so who knows how long the germination took. Good luck with yours.