I would love to share seed from this if I knew exactly what it was. I am pretty sure I obtained a clump of seedlings at a local NARGS meeting, but my notes are failing me. It blooms late, usually Aug-Sept. This year it is warm enough that it is reblooming Oct 26! The plants are over 5 years old, so this seems to be the final size. The color is a clear lemon, the leaves are very narrow. My best guesses from species lists are either much too large or bloom much earlier. (Ithaca NY, USA zone 5 for reference) A larger image facing the flower is attached, except it seems to be lodging itself smack against the one above! Sorry for the clear evidence of poor garden maintenance.