A: Yes, plants belonging to the genus Lilium (Easter lily, etc.) are especially dangerous to cats. All parts of the lily (flower, pollen, stems, leaves and bulbs) can cause lethal kidney failure should Fluffy opt for a taste.
If you suspect or are certain that your cat has consumed any part of the lily plant or flower, then immediately pursue an examination with your veterinarian or emergency veterinary hospital.
Prevention is the best medicine when it comes to keeping your cats safe from lily toxicity. Never leave a pet, especially your feline friend, unobserved in the presence of a seasonal plant like a lily. Their curiosity nearly always supersedes your estimation that the plant will go unexplored. Always obstruct your pet’s access to interesting plants by putting a closed door between your cat and potential life-threatening toxicity. Of course, the safest means of preventing toxicity would be to not allow a plant known to be toxic to your pet into your home.
An extensive list and photos of toxic and non-toxic plants can be found via the American Society for the Prevention of Cruelty to Animals (ASPCA).