I've always called this Clematis ~ Snow White ~ I don't recall the "botanical" name, as I had planted this around 20 yrs. ago. This beauty is growing up and over my back deck . . . I look forward to May each year, as it's a short season for this type of clematis. The flowers on this clematis are as large as dinner plates, and astonishes many people when they see it for the first time! When fully bloomed out, there isn't another plant in my garden that can catch your eye as this true beauty!