Wisteria
Even though wisteria is a beautiful plant to look at, hanging from the top of a ceiling with its bright purple color, it’s one of the most poisonous plants you’ll find in your backyard. The plant contains lectin and wisterin, which, initially, will cause burning in the mouth. If ingested, it may cause dizziness, confusion, headaches, or syncopal episodes, which are temporary drops in blood flow to the brain, where you may lose consciousness. If you eat the berries from the plant, you’ll experience these symptoms about five to seven days later, if you’re still alive (Science Direct).