What is the most poisonous plant in the world?

The most poisonous plant in the world is the Aconitum species, also known as monkshood or wolfsbane. It contains potent alkaloids, such as aconitine, which affect the nervous system and can be fatal if ingested or touched. Even small amounts of the plant can cause symptoms such as nausea, vomiting, and cardiac arrhythmia. Monkshood has historically been used in poisoning and as an arrow poison. Despite its toxicity, it is sometimes used in traditional medicine under controlled circumstances, though it is highly dangerous.