Viridiplantae (literally "green plants") are a

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English ter ...

eukaryotic Eukaryotes () are organisms whose cells have a nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the three domains of life. Bacte ...

organisms that comprise approximately 450,000–500,000 species and play important roles in both terrestrial and aquatic ecosystems. They are made up of the

green algae The green algae (singular: green alga) are a group consisting of the Prasinodermophyta and its unnamed sister which contains the Chlorophyta and Charophyta/ Streptophyta. The land plants (Embryophytes) have emerged deep in the Charophyte alga ...

, which are primarily aquatic, and the land plants (

embryophyte The Embryophyta (), or land plants, are the most familiar group of green plants that comprise vegetation on Earth. Embryophytes () have a common ancestor with green algae, having emerged within the Phragmoplastophyta clade of green algae as sis ...

s), which emerged from within them. Green algae traditionally excludes the land plants, rendering them a

paraphyletic In taxonomy, a group is paraphyletic if it consists of the group's last common ancestor and most of its descendants, excluding a few monophyletic subgroups. The group is said to be paraphyletic ''with respect to'' the excluded subgroups. In ...

group. However it is accurate to think of land plants as a kind of algae. Since the realization that the embryophytes emerged from within the green algae, some authors are starting to include them. They have cells with

cellulose Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell wa ...

in their cell walls, and primary chloroplasts derived from

endosymbiosis An ''endosymbiont'' or ''endobiont'' is any organism that lives within the body or cells of another organism most often, though not always, in a mutualistic relationship. (The term endosymbiosis is from the Greek: ἔνδον ''endon'' "within ...

with

cyanobacteria Cyanobacteria (), also known as Cyanophyta, are a phylum of gram-negative bacteria that obtain energy via photosynthesis. The name ''cyanobacteria'' refers to their color (), which similarly forms the basis of cyanobacteria's common name, bl ...

that contain chlorophylls a and b and lack

phycobilin Phycobilins (from Greek: '' (phykos)'' meaning "alga", and from Latin: ''bilis'' meaning "bile") are light-capturing bilins found in cyanobacteria and in the chloroplasts of red algae, glaucophytes and some cryptomonads (though not in green ...

s. In some classification systems, the group has been treated as a kingdom, under various names, e.g. Viridiplantae, Chlorobionta, or simply

Plant Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae excl ...

ae, the latter expanding the traditional plant kingdom to include the

. Adl'' et al.'', who produced a classification for all

eukaryote Eukaryotes () are organisms whose cells have a nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the three domains of life. Bacter ...

s in 2005, introduced the name Chloroplastida for this group, reflecting the group having primary

chloroplast A chloroplast () is a type of membrane-bound organelle known as a plastid that conducts photosynthesis mostly in plant and algal cells. The photosynthetic pigment chlorophyll captures the energy from sunlight, converts it, and stores it i ...

s with green

chlorophyll Chlorophyll (also chlorophyl) is any of several related green pigments found in cyanobacteria and in the chloroplasts of algae and plants. Its name is derived from the Greek words , ("pale green") and , ("leaf"). Chlorophyll allow plants to ...

. They rejected the name Viridiplantae on the grounds that some of the species are not plants, as understood traditionally. The Viridiplantae are made up of two clades: Chlorophyta and Streptophyta as well as the basal Mesostigmatophyceae and Chlorokybophyceae. Together with

Rhodophyta Red algae, or Rhodophyta (, ; ), are one of the oldest groups of eukaryotic algae. The Rhodophyta also comprises one of the largest phyla of algae, containing over 7,000 currently recognized species with taxonomic revisions ongoing. The majorit ...

and glaucophytes, Viridiplantae are thought to belong to a larger clade called Archaeplastida or Primoplantae. A taxonomic evaluation of

s based on

myosin Myosins () are a superfamily of motor proteins best known for their roles in muscle contraction and in a wide range of other motility processes in eukaryotes. They are ATP-dependent and responsible for actin-based motility. The first myosin (M ...

distribution showed the Viridiplantae lost class-I myosins.

Phylogeny and classification

Simplified phylogeny of the Viridiplantae, according to Leliaert ''et al''. 2012. * Viridiplantae ** Chlorophyta ***core chlorophytes **** Ulvophyceae ***** Cladophorales ***** Dasycladales ***** Bryopsidales *****

Trentepohliales Trentepohliales is an order of Ulvophyceaen green algae.See the NCBI The National Center for Biotechnology Information (NCBI) is part of the United States National Library of Medicine (NLM), a branch of the National Institutes of Health (NI ...

***** Ulvales-

Ulotrichales Ulotrichales is an order of green algae in the class Ulvophyceae.See the NCBIbr>webpage on Ulotrichales Data extracted from the Genera unplaced to family (''incertae sedis ' () or ''problematica'' is a term used for a taxonomic group ...

*****

Oltmannsiellopsidales Oltmannsiellopsidales is an order of green algae in the class Ulvophyceae.See the NCBI The National Center for Biotechnology Information (NCBI) is part of the United States National Library of Medicine (NLM), a branch of the National Institu ...

****

Chlorophyceae The Chlorophyceae are one of the classes of green algae, distinguished mainly on the basis of ultrastructural morphology. They are usually green due to the dominance of pigments chlorophyll a and chlorophyll b. The chloroplast may be discoid, ...

*****

Oedogoniales The Oedogoniales are an order of filamentous freshwater green algae of the class Chlorophyceae. The order is well-defined and has several unique features, including asexual reproduction with zoospores that possess stephanokont flagella: numero ...

*****

Chaetophorales Chaetophorales is an order of green algae in the class Chlorophyceae. Families * '' Aphanochaetaceae'' Oltmanns * '' Barrancaceae'' Caisová et al. * ''Chaetophoraceae Chaetophoraceae is a family of green algae in the order Chaetophora ...

*****

Chaetopeltidales Chaetopeltidales are an order of green algae The green algae (singular: green alga) are a group consisting of the Prasinodermophyta and its unnamed sister which contains the Chlorophyta and Charophyta/Streptophyta. The land plants ( Embryo ...

***** Chlamydomonadales *****

Sphaeropleales Sphaeropleales is an order of green algae that used to be called Chlorococcales. The order includes some of the most common freshwater planktonic algae such as '' Scenedesmus'' and '' Pediastrum''. The Spaeropleales includes vegetatively non-mot ...

**** Trebouxiophyceae *****

Chlorellales The Chlorellales are an order of green algae in the class Trebouxiophyceae The Trebouxiophyceae are a class of green algae, in the division Chlorophyta Chlorophyta or Prasinophyta is a taxon of green algae informally called chlorophyt ...

*****

Oocystaceae Oocystaceae is a family of green algae, in the order Chlorellales. The type genus is '' Oocystis''. List of genera , AlgaeBase AlgaeBase is a global species database of information on all groups of algae, both seaweed, marine and freshwate ...

*****

Microthamniales Microthamniaceae is a family of green algae in the class Trebouxiophyceae.See the NCBI The National Center for Biotechnology Information (NCBI) is part of the United States National Library of Medicine (NLM), a branch of the National Inst ...

*****

Trebouxiales The Trebouxiales are an order of green algae in the class Trebouxiophyceae The Trebouxiophyceae are a class of green algae, in the division Chlorophyta Chlorophyta or Prasinophyta is a taxon of green algae informally called chlorophyt ...

*****'' Prasiola'' clade ****

Chlorodendrophyceae Chlorodendrales are an order of green, flagellated, thecate, unicellular eukaryotes, within the green algae class Chlorodendrophyceae.Becker, B., Marin, B. and Melkonian, M. 1994: Structure, composition, and biogenesis of prasinophyte cell coveri ...

*****

Chlorodendrales Chlorodendrales are an order of green, flagellated, thecate, unicellular eukaryotes, within the green algae class Chlorodendrophyceae.Becker, B., Marin, B. and Melkonian, M. 1994: Structure, composition, and biogenesis of prasinophyte cell cov ...

****

Pedinophyceae Pedinophyceae is a class of green algae in the division Chlorophyta Chlorophyta or Prasinophyta is a taxon of green algae informally called chlorophytes. The name is used in two very different senses, so care is needed to determine the use ...

***

prasinophytes The prasinophytes are a group of unicellular green algae. Prasinophytes mainly include marine planktonic species, as well as some freshwater representatives.Sym, S. D. and Pienaar, R. N. 1993. The class Prasinophyceae. In Round, F. E. and Chapm ...

(paraphyletic) **** Pyramimonadales ****

Mamiellophyceae Mamiellophyceae is a class of green algae in the division Chlorophyta Chlorophyta or Prasinophyta is a taxon of green algae informally called chlorophytes. The name is used in two very different senses, so care is needed to determine the us ...

****

Pycnococcaceae Pycnococcaceae is a family of green algae in the order Pseudoscourfieldiales. The defining features of this family include the single invagination of the pyrenoid where the mitochondrial membrane fits into it Guillard ''et al.'' 1991 Pycnococcus ...

**** Nephroselmidophyceae ****

Prasinococcales Prasinococcaceae is a family of green algae The green algae (singular: green alga) are a group consisting of the Prasinodermophyta and its unnamed sister which contains the Chlorophyta and Charophyta/Streptophyta. The land plants ( Embryoph ...

****

Palmophyllales The Palmophyllales are a deep-branching order of thalloid green alga, possibly forming a sister group to the Chlorophyta. They survive today in deep waters, where predation pressure is reduced. The group contains the genera '' Palmophyllum'', '' ...

** Streptophyta ***

Charophytes Charophyta () is a group of freshwater green algae, called charophytes (), sometimes treated as a division, yet also as a superdivision or an unranked clade. The terrestrial plants, the Embryophyta emerged within Charophyta, possibly from terres ...

(paraphyletic assemblage of freshwater algae). **** Klebsormidiophyceae ****

Phragmoplastophyta The Phragmoplastophyta (Lecointre & Guyader 2006) are a proposed sister clade of the Klebsormidiaceae in the Streptophyte/Charophyte clade. The Phragmoplastophyta consist of the Charophycaea and another unnamed clade which contains the Coleochae ...

**** Mesostigmatophyceae ***** Chlorokybophyceae *****

Charophyceae Charophyceae is a class of charophyte green algae. AlgaeBase places it in division Charophyta. Extant (living) species are placed in a single order Charales, commonly known as "stoneworts" and "brittleworts". Fossil members of the class may be p ...

***** Zygnematophyceae ***** Coleochaetophyceae *** Embryophyta (land plants)

Cladogram

Below is a consensus reconstruction of green algal relationships, mainly based on molecular data. Ancestrally, the green algae were flagellates.

References

{{Taxonbar, from=Q11973077 Biological classification Subkingdoms Taxa named by Thomas Cavalier-Smith