Besides constituting biological diversity and resources, all life forms on earth also form an intricate web of life on the planet in which each functions in a particular way, interacts with, and depends on others to survive and flourish.

Green plants represent a vitally important group of life forms which, through their unique photosynthesis ability, produce oxygen and absorbcarbon in the atmosphere.
Virtually every life form on earth depends on oxygen to survive. Plants also serve as the major source of food for many life forms. Because of immobility, plants in turn depend on the help of other life forms, especially animals, to propagate and disperse.