Engarden

- Beth Ditto

Plant, (kingdom Plantae), any multicellular eukaryotic life form characterized by (1) photosynthetic nutrition (a characteristic possessed by all plants except some parasitic plants and underground orchids), in which chemical energy is produced from water, minerals, and carbon dioxide with the aid of pigments and the radiant energy of the Sun, (2) essentially unlimited growth at localized regions, (3) cells that contain cellulose in their walls and are therefore to some extent rigid, (4) the absence of organs of locomotion, resulting in a more or less stationary existence, (5) the absence of nervous systems, and (6) life histories that show an alteration of haploid and diploid generations, with the dominance of one over the other being taxonomically significant.

Plants range in size from diminutive duckweeds only a few millimeters in length to the giant sequoias of California that reach 90 meters (300 feet) or more in height. An estimated 390,900 different species of plants are known to science, and new species are continually being described, particularly from previously unexplored tropical areas of the world. Plants evolved from aquatic ancestors and have subsequently migrated over Earth's entire surface Earth, inhabiting tropical, Arctic, desert, and Alpine regions. Some plants have returned to an aquatic habitat in either fresh or salt water.

Plants play a vital role in the maintenance of life on Earth. All energy used by living organisms depends on the complex process of photosynthesis, which is mostly carried out by green plants. Radiant energy from the Sun is transformed into organic chemical energy in the form of sugars through the fundamental series of chemical reactions constituting photosynthesis. In nature, all food chains begin with photosynthetic autotrophs (primary producers), including green plants and algae. Primary producers, represented by trees, shrubs, and herbs, are prolific sources of energy in the form of carbohydrates (sugars) stored in the leaves. These carbohydrates, produced in photosynthesis, are broken down in a process called respiration; the smaller units of the sugar molecule and its products fuel numerous metabolic processes. Various parts of the plant (e.g., leaves) are the energy sources that support animal life in different community habitats. A by-product of photosynthesis, oxygen, is essential to animals.

The daily existence of human beings is also directly influenced by plants. Plants furnish food and flavorings; raw materials for industry, such as wood, resins, oils, and rubber; fibers for the manufacture of fabrics and cordage; medicines; insecticides; and fuels. More than half of Earth’s population relies on grasses rice, corn (maize), and wheat as their primary source of food. Apart from their commercial and aesthetic value, plants conserve other natural resources by protecting soils from erosion, controlling water levels and quality, and producing a favorable atmosphere.