Aristotle's Philosophy of Soul

Aristotle believes that natures have to do with internal principles of change. The sunflower displays its internal principle of change, which is its nature. But plants do not perceive, at least according to aristotle. For that, we need to rise a level up the food chain to animals,. who are capable Not only of sense perception, but also of motion from one place to another. This would apply to plato's immaterialist theory of soul and those espoused by the atomists.