Oleander

Russian Tortoise

Agrionemys horsfieldii

Extremely toxic. Contains oleandrin and other cardiac glycosides — a few leaves can be lethal. Do not plant near tortoise enclosures.

Hermann's Tortoise

Testudo hermanni

Extremely toxic — a few leaves can be lethal. Do not plant near enclosures.

Greek Tortoise

Testudo graeca

Cardiac glycosides — a few leaves can be lethal.

Sulcata Tortoise

Centrochelys sulcata

Extremely toxic cardiac glycosides. Do not plant near enclosures.

Leopard Tortoise

Stigmochelys pardalis

Extremely toxic — a few leaves can be lethal.

Red-footed Tortoise

Chelonoidis carbonarius

Extremely toxic. Do not plant near enclosures.

Eastern Box Turtle

Terrapene carolina

Extremely toxic — a few leaves can be lethal.

Yellow-bellied Slider

Trachemys scripta scripta

[confidence: high] [source: ASPCA Animal Poison Control (cross-ref); exotic reptile toxicology review; oleandrin cardiac toxicity in vertebrates] Oleander (Nerium oleander) contains oleandrin, a potent cardiac glycoside; all parts highly toxic and can cause fatal arrhythmia in reptiles including aquatic turtles.

Painted Turtle

Chrysemys picta

[confidence: high] [source: ASPCA Animal Poison Control (cross-ref); exotic reptile toxicology review; oleandrin cardiac toxicity in vertebrates] Oleander (Nerium oleander) contains oleandrin, a potent cardiac glycoside; all parts are highly toxic and can cause fatal arrhythmia in reptiles.

Red-eared Slider

Trachemys scripta elegans

[confidence: high] [source: ASPCA Animal Poison Control (cross-ref); exotic reptile toxicology review; oleandrin cardiac toxicity in vertebrates] Oleander (Nerium oleander) contains oleandrin, a potent cardiac glycoside; all parts are highly toxic and can cause fatal arrhythmia in reptiles including aquatic turtles.