I know this horse has been beaten to death, but looking at all the misleading info about the two on the internet I thought I would help confuse everything even more. Now it is pretty well know (even on the web) that Kwanso is a double and Flore Pleno is a triple, so actually it sounds pretty easy to tell them apart. Until, you start looking and the doubles to most people would look like triples the way the center is formed, still double and triple by looking closer (side by side) is a distinguishable difference.
Even in the ATP data base looking at the pictures I am not sure they are all correct, even the height for Flore Pleno shows to be 30 inches, there is a comment saying that it should be much taller. I think some of mine have nearly reached four feet, so is it Flore Pleno or is the data base wrong, or was it 30 inches in the garden of the person who entered the info?
I have been looking at these for a while and I have two plants in my garden that I believe to be Kwanso and Flore Pleno, growing side by side. I have not entered any of the pics in the ATP data base because I was not sure because of a few discrepancies. So let me ask what you think.
Kwanso: Smaller bloom, less petals, bloom often looks distorted to some extent, and the foliage is bushy looking and short.
Flore Pleno: Much larger bloom, the bloom is more well defined and seldom has the deformed look of some of the Kwanso blooms, the foliage has a very upright tall classic fan shape of a daylily. Often grows very tall in my garden.
Pictures of the two side by side: Flore Pleno on the left, Kwanso on the right;
Flore Pleno on the Right Kwanso on the left;
Kwanso in a pot;
Flore Pleno Bloom;
If these look correct I will enter some photos in the data base.