A proposed phylogeny of the Plantae after Kenrick and Crane is as follows, with modification to the Pteridophyta from Smith et al. The Prasinophyceae may be a paraphyletic basal group to all green plants
From smallest to largest in inclusiveness, these three groupings are:. When the name Plantae or plants is applied to a specific taxon, it is usually referring to one of three concepts
There are around 375,000 species of plants, and each year more are found and described by science. Informally, other creatures that carry out photosynthesis are called plants as well, but they do not constitute a formal taxon and represent species that are not closely related to true plants
Land plants
With a few exceptions among the green algae, all such forms have cell walls containing cellulose, have chloroplasts containing chlorophylls a and b, and store food in the form of starch. Only two groups of algae are considered close relatives of land plants . The Kingdom Plantae is often taken to mean this monophyletic grouping. They undergo closed mitosis without centrioles, and typically have mitochondria with flat cristae. The sister group to the combined embryophytes and charophytes is the other group of green algae , and this more inclusive group is collectively referred to as the green plants or Viridiplantae. The first of these groups is the Charophyta , from which the embryophytes developed
Green algae
Prasinophyceae
About 350,000 species of plants, defined as seed plants, bryophytes, ferns and fern allies, are estimated to exist currently. Plants are living organisms belonging to the kingdom Plantae. As of 2004, some 287,655 species had been identified, of which 258,650 are flowering and 18,000 bryophytes . Green plants, sometimes called metaphytes or viridiplantae, obtain most of their energy from sunlight via a process called photosynthesis. They include familiar organisms such as trees, herbs, bushes, grasses, vines, ferns, mosses, and green algae
All three groups together are generally believed to have a common origin, and so are classified together in the taxon Archaeplastida. The same is true of two additional groups of algae: the Rhodophyta and Glaucophyta. In contrast, most other algae have chloroplasts with three or four surrounding membranes. They are not close relatives of the green plants, presumably acquiring chloroplasts separately from ingested or symbiotic green and red algae. The chloroplasts of green plants are surrounded by two membranes, suggesting they originated directly from endosymbiotic cyanobacteria
†Nematophytes
The algae comprise several different groups of organisms that produce energy through photosynthesis, each of which arose independently from separate non-photosynthetic ancestors. Most conspicuous among the algae are the seaweeds, multicellular algae that may roughly resemble terrestrial plants, but are classified among the green, red, and brown algae. Most algae are no longer classified within the Kingdom Plantae. Each of these algal groups also includes various microscopic and single-celled organisms
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. About 350,000 species of plants, defined as seed plants, bryophytes, ferns and fern allies, are estimated to exist currently
In Linnaeus’ system, these became the Kingdoms Vegetabilia and Animalia . Aristotle divided all living things between plants , and animals . However, these are still often considered plants in many contexts, both technical and popular. 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
They are not related to any of the photosynthetic groups, but are close relatives of animals. Fruiting bodies, of which mushrooms are most familiar, are the reproductive structures of fungi. Fungi were previously included in the plant kingdom, but are now seen to be more closely related to animals. Therefore, the fungi are in a kingdom of their own. Most fungi are formed by microscopic structures called hyphae, which may or may not be divided into cells but contain eukaryotic nuclei. Unlike embryophytes and algae, fungi are not photosynthetic, but are saprotrophs: obtaining food by breaking down and absorbing surrounding materials