Chrysanthemums and Cats

Question
Exactly how poisonous are chrysanthemums to cats?  I received chrysanthemums as a gift, and while I was searching for a vase left them on my kitchen table.  Of course, my cat went to check them out.  I think he just sniffed a little.  At the most, he would've eaten a leaf.  I wasn't away long.  But he definitely came in contact with him.  My cat seems to be acting normal, I'm just curious.  If I don't see any symptoms within 12 hours, should I assume he's okay?

Answer
I am not home where my lists are but you can look it up by Googling plants that are poisonous to cats. Purdue Medical has a very comprehensive list of poisonous plants.

If I recall, this plant is not poisonous at all, but you need to look it up to be sure.