The greatest contribution of plants is that they gave us life. I mean, if not because of them, we might not be here today. Plants gave us many things so that we can survive here on earth. They gave us oxygen and many of them serve as a food to us. And many of the things we are using now are originally made from them. They also serve as a medicine in some cases. And sometimes, they also save us from calamities such as storms, flood, landslides, etc., that's why they contributed so much to the living things on earth.