Viridiplantae (literally "green plants") are a clade of

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. Bact ...

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 alg ...

, 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 si ...

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

paraphyletic In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...

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 wall ...

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'' "withi ...

with cyanobacteria that contain chlorophylls a and b and lack phycobilins. 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 Photosynthesis, photosynthetic eukaryotes of the Kingdom (biology), kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all curr ...

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. Bact ...

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 ...

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 and

glaucophyte The glaucophytes, also known as glaucocystophytes or glaucocystids, are a small group of unicellular algae found in freshwater and moist terrestrial environments, less common today than they were during the Proterozoic. The stated number of speci ...

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

s based on myosin 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 ***** Ulvales- Ulotrichales *****

Oltmannsiellopsidales Oltmannsiellopsidales is 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 ...

**** Chlorophyceae *****

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: numerous ...

***** Chaetophorales *****

Chaetopeltidales Chaetopeltidales are an order of green algae in the class 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 ...

*****

Chlamydomonadales Chlamydomonadales, also known as Volvocales, are an order of flagellated or pseudociliated green algae, specifically of the Chlorophyceae.See the NCBIbr>webpage on Chlamydomonadales Data extracted from the Chlamydomonadales can form planar or ...

*****

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.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 Insti ...

***** Oocystaceae ***** Microthamniales *****

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. Their circumscription within the green algae is not well established due to the need for ...

*****'' Prasiola'' clade **** Chlorodendrophyceae ***** Chlorodendrales **** Pedinophyceae *** prasinophytes (paraphyletic) **** Pyramimonadales **** Mamiellophyceae ****

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 Pycnococcu ...

**** Nephroselmidophyceae **** Prasinococcales **** Palmophyllales ** Streptophyta *** Charophytes (paraphyletic assemblage of freshwater algae). **** Klebsormidiophyceae **** Phragmoplastophyta **** Mesostigmatophyceae ***** Chlorokybophyceae ***** Charophyceae ***** Zygnematophyceae ***** Coleochaetophyceae ***

Embryophyta 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 ...

(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