PLANT KINGDOM Plants are a major group of life forms and

include familiar organisms such as trees, herbs, bushes, grasses, vines, ferns, mosses, and green algae.

About 350,000 species of plants, defined as seed plants, bryophytes, ferns and fern allies, are estimated to exist currently. As of 2004, some 287,655 species had been identified, of which 258,650 are flowering and 15,000 bryophytes

Definition

Aristotle divided all living things between plants (which generally do not move), and animals (which often are mobile to catch their food). In Linnaeus' system, these became the Kingdoms Vegetabilia (later Metaphyta or Plantae) and Animalia

Plantae or plants

When the name Plantae or plants is applied to a specific taxon, it is usually referring to one of three concepts. From smallest to largest in inclusiveness, these three groupings are:

Land plants, also known as Embryophyta or Metaphyta. As the narrowest of plant categories, this is further delineated below

Green plants - also known as Viridiplantae, Viridiphyta or Chlorobionta - comprise the above Embryophytes, Charophyta and Chlorophyta (i.e., green algae such as sea lettuce). It is this clade which is mainly the subject of this article.

Plastida or Primoplantae - comprises the green plants above, as well as Rhodophyta (red algae) and Glaucophyta (simple glaucophyte algae).

Diversity

About 350,000 species of plants, defined as seed plants, bryophytes, ferns and fern allies, are estimated to exist currently. As of 2004, some 287,655 species had been identified, of which 258,650 are flowering plants, 16,000 bryophytes, 11,000 ferns and 8,000 green algae.

Diversity of living plant divisions Informal group

Division name Common name

No. of living species

PhylogenyA proposed phylogeny of the Plantae

after Kenrick and Crane[15], with modification to the Pteridophyta from Smith et al.[16] The Prasinophyceae may be a paraphyletic basal group to all green plants.

EmbryophytesMost familiar are the multicellular land

plants, called embryophytes. They include the vascular plants, plants with full systems of leaves, stems, and roots. They also include a few of their close relatives, often called bryophytes, of which mosses and liverworts are the most common.

Life processesGROWTH

GROWTH Most of the solid material in a plant is taken

from the atmosphere. Through a process known as photosynthesis, plants use the energy in sunlight to convert carbon dioxide from the atmosphere into simple sugars. These sugars are then used as building blocks and form the main structural component of the plant. Plants rely on soil primarily for support and water (in quantitative terms), but also obtain nitrogen, phosphorus and other crucial elemental nutrients. For the majority of plants to grow successfully they also require oxygen in the atmosphere and around their roots for respiration. However, a few specialized vascular plants, such as Mangroves, can grow with their roots in anoxic conditions.

Importance

The study of plant

The study of plant uses by people is termed economic botany or ethnobotany. They are often used as synonyms but some consider economic botany to focus mainly on uses of modern cultivated plants, while ethnobotany studies uses of indigenous plants by native peoples. Human cultivation of plants is part of agriculture, which is the basis of human civilization. Plant agriculture is subdivided into agronomy, horticulture and forestry

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