Plants have been on Earth for billions of years. They can be found on land, oceans, and even deserts. Plants are multicellular, eukaryotic organisms that have cells that differ from us humans. They have cell walls, which is made from cellulose, and chlorophyll, which is a green pigment that is necessary for a process called photosynthesis. Photosynthesis is the process where plants take in CO2, sunlight, and water to make glucose for energy. Their waste product is oxygen. This process allows the majority of the plants to be autotrophs. This flowering plant is one example of the over 250,000 plants on Earth.