Plants

Plants are a major group of living things including familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, and mosses. About 350,000 species of plants, defined as seed plants, bryophytes, ferns and fern allies, have been estimated to exist. As of 2004, some 287,655 species had been identified, of which 258,650 are flowering and 15,000 bryophytes. Plants are mostly autotrophs, organisms that obtain energy from sunlight or organisms that make their own food. Most plants carry out a process called photosynthesis, which occurs in the chloroplasts of plants.


Classification

Aristotle divided all living things between plants, which generally do not move, and animals. In Linnaeus' system, these became the Kingdoms Vegetabilia (later Plantae) and Animalia. Since then, it has become clear that the Plantae as originally defined included several unrelated groups, and the fungi and several groups of algae were removed to new kingdoms. However, these are still often considered plants in many contexts. Indeed, any attempt to match "plant" with a single taxon is doomed to fail, because plant is a vaguely defined concept unrelated to the presumed phylogenic concepts on which modern taxonomy is based.

When the name Plantae is applied to a specific taxon, it is usually one of three groups, each more inclusive than the last. From smallest to largest these are:

* Land plants (also known as Embryophyta)—see below.
* Green plants (also known as Viridiplantae or Chlorobionta) comprising Embryophytes and green algae. Essentially the subject of this article.
* Primoplantae (also known as Plantae sensu lato, Plastida, or Archaeplastida) comprises green plants, red algae and glaucophyte algae. The broadest plant clade, this comprises the eukaryotes that acquired their chloroplasts directly by engulfing bacteria.

Informally, other creatures that carry out photosynthesis are called plants as well, but they do not constitute a formal taxon.