Plants are organisms that belong to the plant kingdom comprising of trees, bushes, shrubs, grasses, vines, mosses, ferns and green algae. While most plants grow on the land, many thrive in the water as well. Some plants can grow as tall as 100 meters. Plants lie at the base of almost all food chains and are the most important constituent of the Earth's biosphere. Plants evolved on land around 500 million years back and currently there are around 350,000 species of plants.