There is a widely held belief among the general public that animals instinctively know not to eat poisonous plants. This, unfortunately, is definitely not the case. Our experience at the Hennepin Regional Poison Center indicates that plants represent the major source of poisoning in small animals. In addition, plants are a major cause of poisoning among grazing animals as well. In a review of seventy cases of illness in tortoises, the authors of the following article cite an incident which may be the only reported case of possible plant poisoning in a reptile. The following information is excerpted from that report.
One tortoise was presented having died suddenly with no apparent illness. The carcass was in good condition and there were no external or oral lesions. Post-mortem examination revealed a pale liver and slight yellow discoloration of the body fat. No gross abnormalities were observed on initial examination of other viscera and both stomach and bowel were distended with ingesta. The large and small intestines were found to contain partly-digested green plant material (mostly dandelions and grass). The stomach, however, was packed with buttercup flowers, Ranunculus sp., and there was a 1.5 cm diameter, hemorrhagic area in the mucosa of the greater curvature of the gastric fundus. No other lesions were found.