Plants (botanical)

Plants, also called green plants (Viridiplantae in Latin), are living organisms of the kingdom Plantae including such multicellular groups as flowering plants, conifers, ferns and mosses, as well as, depending on definition, the green algae, but not red or brown seaweeds like kelp, nor fungi or bacteria

Precise numbers are difficult to determine, but, there are thought to be 300–315 thousand species of plants, of which the great majority, some 260–290 thousand, are seed plants (see the table below). Green plants provide most of the world's free oxygen and are the basis of most of the earth's ecologies, especially on land. Plants described as grains, fruits and vegetables form mankind's basic foodstuffs, and have been domesticated for millennia. Plants enrich our lives as flowers and ornaments. Until recently and in great variety they have served as the source of most of our medicines and drugs. Their scientific study is known as botany.

Psychologists are interested in plant for a number of reasons.
 * Plants may cause harm to animals, including people.
 * Plants that produce windblown pollen invoke allergic reactions in people who suffer from hay fever. Some plants cause allergic reactions when ingested, while other plants cause food intolerances that negatively affect health.
 * A wide variety of plants are poisonous. *Toxalbumins are plant poisons fatal to most mammals and act as a serious deterrent to consumption.
 * Several plants cause skin irritations when touched, such as poison ivy. Certain plants contain psychotropic chemicals, which are extracted and ingested or smoked, including tobacco, cannabis (marijuana), cocaine and opium. Smoking causes damage to health or even death, while some drugs may also be harmful or fatal to people.
 * Both illegal and legal drugs derived from plants may have negative effects on the economy, affecting worker productivity and law enforcement costs.