Without plants, no animals would be able to survive on earth. They transform energy from the sun into organic material that we humans and other animals can use to sustain ourselves. Plants also convert carbon dioxide into carbon, which they use to grow, and oxygen, which is released back into the atmosphere for us to breathe. The biology of plants can be broken down into six main parts – each with a specific purpose: roots, stems, leaves, flowers, fruit and seeds.
Roots absorb water and nutrients from the soil using a vast network of larger roots with many smaller offshoots. They also anchor the plant to the ground, usually making it able to withstand a battering from wind and rain.
The stems of a plant transport water and nutrients through the plant. Water is constantly moving through a plant, from the roots to the leaves, in an action similar to that of a conveyor belt. This keeps the plant rigid, meaning when a plant is starved of water it wilts. Keeping the plant upright and supported is an important job of the stem.
Leaves are very important because these are where carbon dioxide is taken into the plant and where it is split into carbon and oxygen in a process called photosynthesis. The plant needs the essential ingredients of chlorophyll and sunlight to do this, and chlorophyll is predominantly stored in the leaves. Leaves in some plants can also help to direct more rain to its roots. Other plants use their leaves to keep away predators, like stinging nettles and holly.
Flowers hold the male and female reproductive parts of the plant - pollen and ovules. They are bright and attractive because they need to attract insects like bees and butterflies to feed on their nectar. When they do so, some of the pollen rubs off onto them and they carry this to the next plant on which the ovules become pollinated which starts the reproductive cycle. This creates seeds.
Fruit grows from fertilised flowers and contain seeds. The fruit's job is to protect the seeds and help disperse them. Many unlikely things are fruits in the botanical sense, but not in the culinary sense, such as nuts. They often store valuable – and tasty – nutrients like sugars.
Seeds contain all the necessary material for a new plant to be formed and grow. Most simply drop to the ground next to where the adult plant, and grow. They need just fertile land and water to germinate. Some seeds pass through animals which eat the fruit and then deposit them in a fresh batch of manure on the ground.