Flora was once known as the Roman goddess of flowers, though today we use the term to refer to plant life, including trees. Vascular plants have specialized supporting and water-conducting tissue, and typically possess roots, stems and leaves. Nonvascular plants, such as mosses, lack an internal conducting system for water and nutrients, so they depend on their immediate surroundings for moisture.
To be considered a plant, an organism must possess certain characteristics: photosynthesis, cellulose, stationary existence and lack a nervous system.
Photosynthesis is the process by which plants transform energy from the sun into the energy they need to survive. Through photosynthesis, plants are able to convert water, carbon dioxide and minerals into oxygen and energy. Without photosynthesis, there would be little food or other organic matter on Earth; the air would be full of carbon dioxide; and most organisms, including humans, would disappear.
Cellulose is the basic structural component of plant cell walls, making them rigid. Enabling the leaves and stems of a plant to stand up straight is an important function of cellulose. Plants also lack the means to move on their own as well as a nervous system. The nervous system is a group of organized cells that allow an organism to respond to sensory impulses.
