Be very careful about which plants your cat is chewing on. Some are poisionous to cats:
Baneberry and Doll's-eyes
Amaryllis
Andromeda
Appleseeds (cyanide)
Arrowgrass
Avocado
Azalea
Belladonna or Deadly Nightshade
Bleeding Heart, Squirrel Corn, Dutchman's Breeches
Bittersweet
Boxwood
Buttercup
Cabbage, Turnips, Broccoli, Mustard
Caladium
Castor Bean
Celandine
Cherry pits
Chokecherry
Climbing lily
Commercial Onions, Wild Onions, Swamp Onions, and Chives
Corn Cockle
Crown Vetch
Daffodil
Daphne
Delphiniums and Larkspurs
Dieffenbachia
Dogbane
Elephant Ear
Elderberry
English Ivy
Ergot
Fiddleneck
Foxglove
Hemlock
Horse Chestnut, Buckeye
Hyacinth
Hydrangea
Iris
Jack-in-the-Pulpit
Jimsonweed, Downy Thornapple, Devil's Trumpet, and Angel's Trumpet
Lamb's Quarters
Larkspur
Laurel
Lily-of-the-Valley
Locoweed
Marigold
Marijuana
Marsh Marigold or Cowslip
Milkweed
Mistletoe
Monkey Agaric, Panther Cap, Death Cap, and Death Angel Mushrooms
Monkshood, Aconite, or Wolfsbane
Mushrooms
Narcissus
Nightshade
Oleander
Peach
Philodendron
Pigweed
Poison Hemlock
Prickly Poppy or Mexican Poppy
Rosary Pea
Tung Oil Tree, Candlenut Tree
Water Hemlock or Cowbane
Yellow Star Thistle