While plants are often called "plant-like substances," they are actually classified as their own kingdom, distinct from animals, fungi, and bacteria.
The process by which plants produce their own food is called photosynthesis. They use sunlight, water, and carbon dioxide to create sugar (glucose) for energy, and release oxygen as a byproduct.
So, while you could technically call them "plant-like substances," it's more accurate and scientifically sound to refer to them simply as plants.
