6. Rhubarb
Rhubarb’s famously tart stalks are a beloved pie filling and preserve ingredient. But don’t let those ruby red stems fool you – the leaves of this common plant contain soluble oxalates, potent toxins that can rapidly cause breathing difficulties, burning in the mouth and throat, nausea, and even comas or death in worst cases.
These toxic leaves have caused multiple poisonings when accidentally consumed. In fact, rhubarb was weaponized as a biological agent during World War I!
While the stalks themselves are safe when properly prepared, rhubarb greenery should always be avoided to prevent ingesting concentrated levels of this natural pesticide.