What are the Parts of a Plant? Let’s go from the bottom to the top: ROOTS, STEM, LEAVES, FLOWERS. Who Needs Plants? EVERYONE! Plants give off a gas called oxygen which is what we (and animals) need to breathe in to live. A plant's life cycle is how long a plant lives or how long it takes to grow, flower, and make seeds. All plants need water, air, and warm temperatures to grow. Read More...