Plants known to be toxic to Tortoises

• Aconite ( monks hood )
• Autumn crocus
• Baneberry
• Betal nut palm
• Belladonna
• Boxwood
• Crocus
• Daffodil
• Death camus
• Deadly nightshade
• Destroying angel ( death cap )
• Fly agaric ( aminata, deathcap )
• Foxglove
• Hemlock
• Henbane
• Hydrangea
• Jimson weed ( thorn apple )
• Lambkill ( sheep laurel )
• Lily of the valley
• Locoweed
• Lupin
• Mescal
• Mistletoe
• Monkshood
• Nicotine, tree, bush, flowering
• Nightshades
• Oleander
• Peony
• Poison hemlock
• Poison ivy
• Poison oak
• Poison sumac
• Potato ( leaves )
• Rhubarb ( leaves )
• Rhododendron
• Water hemlock
• Yew

There are many other poisonous plants but these are the ones known to be toxic to tortoises.

Taken from A. C. Highfield's   The Tortoise & Turtle Feeding Manual