Catherine Delahaye/Getty Have you ever eaten a green potato, or a bunch of rhubarb leaves? Hopefully not, because these two plant parts can be toxic to humans. While they may seem edible, they contain chemicals that can make you seriously ill. Over centuries, humans have learnt which plants are safe to eat and which are not, often by combining ancient knowledge with modern science. The power of plants Without plants, we would struggle to get the nutrients we need. Crops such as wheat and rice