The Oak Tree (Quercus) has poisonous (as well as addictive) leaves and acorns. Tannic acid is the poisonous component in oak trees that leads to kidney damage and gastroenteritis in the majority of livestock. Symptoms include lack of appetite, depression, constipation, diarrhoea, bloody urination, and colic. Humans are able to ingest acorns after they are processed and therefore detoxified.

The Oak Tree (Quercus) has poisonous (as well as addictive) leaves and acorns. Tannic acid is the poisonous component in oak trees that leads to kidney damage and gastroenteritis in the majority of livestock. Symptoms include lack of appetite, depression, constipation, diarrhoea, bloody urination, and colic. Humans are able to ingest acorns after they are processed and therefore detoxified.