Aspca.org has a wonderful list of toxic plants for your cats. You will amazed that some of the plants that we have inside our home or garden can endanger our pet cats. Aloe, apple, California ivy, chrysantemum, Peach and poison daisy are only some of the plants that can be harmful to them.
Check their "List of Plants Toxic to Cats" to find out if any of your plants included in the list.