Plants describes any type of species that grows in dirt, rocks, in or near water and other locations. There is a wide variety of plant-life on Earth, as well as on other worlds in the universe.
Plants, for the most part, unlike animals, do not have brains, and therefore do not have the ability to think. There are a few exceptions to this rule though. For example, the Plant Soldiers do have the ability to think, as they were engineered as such, and because of that, they are capable of walking about just like an animal.