Posted: 29/10/2015 at 18:08
C. rotundifolia is my favourite
C. persicifolia goes OK and a tallish one that comes in white and mauve, I've never worked out which one it is, a species I should think. C. trachelium is another reliable one, I like reliable
Some of the others you mention Kathy have been invasive in the root and pathetically poor in the flower for me.
I've sown C thyrsoides recently and await action.