Corinne, the seed that produced the plants in the photo was over 20 years old, and was kept in the deep freeze until I planted it. I have no record of where it came from. I received C. convulvulaceae from the North American Rock Garden Society, and from Jim and Jenny Archibald, in Winter 2006. I haven't grown those seeds yet. I also have C. convulvulaceae alba and C. vincaeflora. My C. vincaeflora are now four feet tall, growing on a tomato cage out in the yard, with morning sun and afternoon shade. I'll take a photo tomorrow. They are setting tons of seed, but it's not ripe yet. If you want some, let me know.
I am concerned that the roots will not survive the wet winter outdoors, so I will dig them when they go dormant and store them in dryish peat moss in the fridge over the winter.