The Plant Kingdom contains all multi-cellular plants that use sunlight and water to produce their own food through a process called photosynthesis. Virtually all living organisms depend on plants in some way. Most importantly, plants produce the oxygen that we breathe. Animals also eat plants in order to obtain energy. Organisms in the Plant Kingdom differ from other kingdoms in that they all contain chlorophyll which is necessary to perform photosynthesis, they are stationary and cannot move from one spot to another, and their cell walls contain cellulose. Cellulose is a material that gives plants their crispness.
There are more than 260,000 known species of plants. These plants are further dividing into subkingdoms and super-divisions. These divisions are based on how the plant obtains its water, their reproduction method, and their size. Some plants absorb water through their roots while others circulate it through their bodies. Some plants use pollination to reproduce while others produce bulbs that can grow into new plants without pollination. Plants can be very small or grow to be over 100 meters tall.
Plants are said to have evolved before animals and lie at the start of most food chains. Without plants, most living organisms could not survive. Luckily, plants can thrive in even the harshest conditions. Even the cold tundra regions of the Earth contain some vegetation.