This is the Chocolate Soldier Columbine. I don't think I have to say anything more than it is a Top 10 favorite of mine. The blooms aren't really all that showy, but they are simply so unusual one just cannot get enough of them.
Easy to grow from seed, they can bloom the first year if tended to from the start. They are small-ish, only about 15-20" tall and wide, and appear to be pretty tough. No mildew in sight!