" I'm hoping that someone here knows for sure if daylilies are truly poisonous to cats."
Nobody knows for sure, there have never been any actual tests. While there are certainly some botanically ignorant statements floating around in veterinary circles (even pictures in technical articles that show lilies labeled daylily) and many people think it is a case of misidentification (just look at any daylily forum on Facebook and see how many pictures of Lilium are posted!) there's no way to be certain that no cat would ever be affected by eating a daylily. Many people say their cats have eaten daylily flowers, seedling leaves etc. for years without any problem but whether there any exceptions to this, we just don't know.
