Plant classification is a process similar to the classification of animals, which is a scientific method of separating plants into different related species, depending on their characteristics. As animals have large areas of distinction that act as overall methods of initial classification, such as warm-blooded mammals from cold-blooded reptiles, plants also are initially broken down by general characteristics. These include plants that produce seed or don't, and those that are flowering plants or not. Characteristics that separate plants from one another such as those that live just one growing season known as annuals, versus those that live for many seasons known as perennials, are also important details used in classification.
The classification of plants, like that of animals, is broken down by various levels, from the basic plant Kingdom membership for all plants of Plantae, down to the specific individual one known as the species, where unique characteristics are most predominant. In the plant world, the three largest formal areas of plant classification that are seen as the most important are the increasingly specialized categories of Family, Genera or Genus, and Species. Fungi are an important plant classification as well, and are considered to be among the most primitive of plants.
Fungi plants don't produce seeds or flowers and are a minority group with about 90,000 types. Mushrooms themselves make up a third of these with 31,496 species identified on Earth as of 2010. The plant classification group with the smallest number of member species known to science is that of the brown algae, consisting of only 3,067 species as of 2010, as opposed to red and green algae, where 10,134 species have been identified.
While fungi are a narrow area of plant classification in general, this includes plant types that range from algae and mosses to mushrooms, molds, and yeast. This plant classification is further broken down by species that do or do not produce leaves, stems, and roots. While ferns are within the plant classification for non-seed producing examples, mosses often look like they have roots or leaves though they actually do not, and are classified on a different branch of the same family tree from that of ferns.
The broadest area of the plant kingdom consists of those species that do produce seeds. These examples are first divided by whether or not they are flowering plants. Various grain crops and grasses are among non-flowering plants, whereas many, but not all, trees and shrubs produce flowers.
As the plant classification levels become increasingly distinctive, the numbers of examples rise astronomically. Within the Family level for plant classification, only 150 to 500 plant families are known to exist in all of nature. By contrast, there are estimated as of 2008 to be between 280,000 and 400,000 individual plant species.
The process of plant classification is an important arena in science, both to preserve species and study them so that they don't go extinct, and to understand the role they play within ecosystems. Plants make up about a quarter of all the species identified on Earth as of 2010, with current total numbers being in the range for all living things, excluding livestock and bacteria of 1,700,000. Mammals are a very small group among species, comprising only 5,490 members, and insect species are the largest group on Earth, with an estimated 1,000,000 species identified as of 2010.