This has been a GREAT thread, such great information.
The problem with vomiting after a cat eats daylily leaves is that many cats will vomit after eating something like that. I know my cats will vomit after eating grass - and the grass isn't poisonous - I always believed that they ate grass because they had an upset stomach, and did so to make themself vomit (or is that an old wive's tale?)
I know at least one of my cats ate my seedlings, I don't remember if he vomited. (he has since passed away several years later of bladder cancer) That was the cat I was referring to when I completed the survey. ~Jan