Chlorophyta or Prasinophyta is a

taxon In biology, a taxon ( back-formation from '' taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular n ...

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 ...

informally called chlorophytes. The name is used in two very different senses, so care is needed to determine the use by a particular author. In older classification systems, it refers to a highly

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 of ''all'' the green algae within the green plants (

Viridiplantae Viridiplantae (literally "green plants") are a clade of eukaryotic 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, which a ...

) and thus includes about 7,000

species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...

of mostly aquatic photosynthetic

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. In newer classifications, it refers to the sister clade of the streptophytes/ charophytes. The clade Streptophyta consists of the

Charophyta 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 terr ...

in which the

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) emerged. In this latter sense the Chlorophyta includes only about 4,300 species. About 90% of all known species live in freshwater. Like the land plants ( embryophytes:

bryophyte The Bryophyta s.l. are a proposed taxonomic division containing three groups of non-vascular land plants ( embryophytes): the liverworts, hornworts and mosses. Bryophyta s.s. consists of the mosses only. They are characteristically limited ...

s and tracheophytes), green algae (chlorophytes and charophytes besides embryophytes) contain chlorophyll a and chlorophyll b and store food as

starch Starch or amylum is a polymeric carbohydrate consisting of numerous glucose units joined by glycosidic bonds. This polysaccharide is produced by most green plants for energy storage. Worldwide, it is the most common carbohydrate in human diets ...

in their

plastids The plastid (Greek: πλαστός; plastós: formed, molded – plural plastids) is a membrane-bound organelle found in the cells of plants, algae, and some other eukaryotic organisms. They are considered to be intracellular endosymbiotic cy ...

. With the exception of Palmophyllophyceae,

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 more genetic studies at higher levels within the group. Genera without inter ...

, Ulvophyceae and Chlorophyceae, which show various degrees of multicellularity, all the Chlorophyta lineages are unicellular. Some members of the group form symbiotic relationships with

protozoa Protozoa (singular: protozoan or protozoon; alternative plural: protozoans) are a group of single-celled eukaryotes, either free-living or parasitic, that feed on organic matter such as other microorganisms or organic tissues and debris. Histor ...

, sponges, and cnidarians. Others form symbiotic relationships with fungi to form lichens, but the majority of species are free-living. Some conduct sexual reproduction, which is oogamous or isogamous. All members of the clade have motile flagellated swimming cells. While most species live in freshwater habitats and a large number in

marine habitats Marine habitats are habitats that support marine life. Marine life depends in some way on the saltwater that is in the sea (the term ''marine'' comes from the Latin ''mare'', meaning sea or ocean). A habitat is an ecological or environmenta ...

, other species are adapted to a wide range of land environments. For example, ''Chlamydomonas nivalis'', which causes Watermelon snow, lives on summer alpine snowfields. Others, such as '' Trentepohlia'' species, live attached to rocks or woody parts of trees. '' Monostroma kuroshiense'', an edible green alga cultivated worldwide and most expensive among green algae, belongs to this group.

Ecology

Species of Chlorophyta (treated as what is now considered one of the two main clades of

) are common inhabitants of marine, freshwater and terrestrial environments.Graham LE, Graham JM, Wilcox LW (2009) ''Algae''. 2nd Edition. Benjamin Cummings (Pearson), San Francisco, CA Several species have adapted to specialised and extreme environments, such as deserts, arctic environments, hypersaline habitats, marine deep waters, deep-sea hydrothermal vents and habitats that experiences extreme changes in temperature, light and salinity. Some groups, such as the Trentepohliales are exclusively found on land. Several species of Chlorophyta live in symbiosis with a diverse range of

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, including

fungi A fungus (plural, : fungi or funguses) is any member of the group of Eukaryote, eukaryotic organisms that includes microorganisms such as yeasts and Mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified ...

(to form lichens),

ciliate The ciliates are a group of alveolates characterized by the presence of hair-like organelles called cilia, which are identical in structure to eukaryotic flagella, but are in general shorter and present in much larger numbers, with a differen ...

s, forams,

cnidarian Cnidaria () is a phylum under kingdom Animalia containing over 11,000 species of aquatic animals found both in Fresh water, freshwater and Marine habitats, marine environments, predominantly the latter. Their distinguishing feature is cnidocyt ...

s and molluscs. Some species of Chlorophyta are

heterotrophic A heterotroph (; ) is an organism that cannot produce its own food, instead taking nutrition from other sources of organic carbon, mainly plant or animal matter. In the food chain, heterotrophs are primary, secondary and tertiary consumers, but ...

, either free-living or

parasitic Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson ha ...

. Others are

mixotroph A mixotroph is an organism that can use a mix of different Primary nutritional groups, sources of energy and carbon, instead of having a single trophic mode on the continuum from complete autotrophy at one end to heterotrophy at the other. It is est ...

ic bacterivores through

phagocytosis Phagocytosis () is the process by which a cell uses its plasma membrane to engulf a large particle (≥ 0.5 μm), giving rise to an internal compartment called the phagosome. It is one type of endocytosis. A cell that performs phagocytosis i ...

. Two common species of the heterotrophic green alga '' Prototheca'' are

pathogenic In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a ger ...

and can cause the disease protothecosis in humans and animals.

Classifications

Characteristics used for the classification of Chlorophyta are: type of zoid,

mitosis In cell biology, mitosis () is a part of the cell cycle in which replicated chromosomes are separated into two new nuclei. Cell division by mitosis gives rise to genetically identical cells in which the total number of chromosomes is maint ...

(karyokynesis),

cytokinesis Cytokinesis () is the part of the cell division process during which the cytoplasm of a single eukaryotic cell divides into two daughter cells. Cytoplasmic division begins during or after the late stages of nuclear division in mitosis and me ...

, organization level,

life cycle Life cycle, life-cycle, or lifecycle may refer to: Science and academia * Biological life cycle, the sequence of life stages that an organism undergoes from birth to reproduction ending with the production of the offspring * Life-cycle hypothesi ...

, type of gametes,

cell wall A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane. It can be tough, flexible, and sometimes rigid. It provides the cell with both structural support and protection, and also acts as a filtering mec ...

polysaccharides Polysaccharides (), or polycarbohydrates, are the most abundant carbohydrates found in food. They are long chain polymeric carbohydrates composed of monosaccharide units bound together by glycosidic linkages. This carbohydrate can react with w ...

and more recently

genetic data In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding gen ...

Phylogeny

A newer proposed classification follows Leliaert et al. 2011 and modified with Silar 2016, Leliaert 2016 and Lopes dos Santos et al. 2017 for the green algal clades and Novíkov & Barabaš-Krasni 2015 for the land plants clade. Sánchez-Baracaldo et al. is followed for the basal clades. A 2020 paper places the "Prasinodermophyta" (i.e.

Prasinodermophyceae ''Prasinoderma'' is a genus of green algae in the phylum Prasinodermophyta The Prasinodermophyta are a proposed basal Viridiplantae clade, as sister of another clade comprising the Chlorophyta and the Streptophyta. It consists of the Prasinode ...

+ Palmophyllophyceae) as the basal Viridiplantae clade.

Leliaert ''et al''. 2012

Simplified phylogeny of the Chlorophyta, according to Leliaert ''et al''. 2012. Note that many algae previously classified in Chlorophyta are placed here in Streptophyta. *

**Chlorophyta ***core chlorophytes **** Ulvophyceae ***** Cladophorales ***** Dasycladales *****

Bryopsidales Bryopsidales is an order of green algae, in the class Ulvophyceae. Characteristics The thallus is filamentous and much branched and may be packed into a mass. It is coenocytic, having multi-nucleate cells consisting of cytoplasm contained with ...

***** Trentepohliales *****

Ulvales Ulvales is an order of green alga 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) ha ...

- 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 ...

****

*****

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 Oocystaceae is a family of green algae, in the order Chlorellales. The type genus is '' Oocystis''. List of genera , AlgaeBase accepted the following genera: *'' Amphikrikos'' Korshikov – 6 species *'' Catenocystis'' F.Hindák – 2 species * ...

***** 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 *** 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 ***

charophyte 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 terr ...

s **** Mesostigmatophyceae **** Chlorokybophyceae **** Klebsormidiophyceae **** Charophyceae **** Zygnematophyceae **** Coleochaetophyceae ***

(land plants)

Pombert ''et al''. 2005

A possible classification when Chlorophyta refers to one of the two clades of the Viridiplantae is shown below. * Class Prasinophyceae T. A. Chr. ex Ø. Moestrup & J. Throndsen * Class Chlorophyceae Wille * Class

T. Friedl * Class Ulvophyceae

Lewis & McCourt 2004

* Division Chlorophyta (green algae sensu stricto) ** Subdivision Chlorophytina *** Class Chlorophyceae (chlorophytes) **** Order

(+ some Chlorococcales + some Tetrasporales + some

Chlorosarcinales 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 ...

) **** Order

(sensu Deason, plus ''Bracteacoccus, Schroederia, Scenedesmaceae, Selanastraceae'') **** Order

**** Order

**** Order Chaetophorales **** Incertae Sedis (''Cylindrocapsa'' clade, ''Mychonastes'' clade) *** Class Ulvophyceae (ulvophytes) **** Order Ulotrichales **** Order

**** Order Siphoncladales/ Cladophorales **** Order Caulerpales **** Order Dasycladales *** Class

(trebouxiophytes) **** Order

**** Order Microthamniales **** Order Prasiolales **** Order

*** Class Prasinophyceae (prasinophytes) **** Order Pyramimonadales **** Order Mamiellales **** Order Pseudoscourfieldiales **** Order Chlorodendrales **** Incertae sedis (Unnamed clade of coccoid taxa) * Division

(charophyte algae and embryophytes) ** Class Mesostigmatophyceae (mesostigmatophytes) ** Class Chlorokybophyceae (chlorokybophytes) ** Class Klebsormidiophyceae (klebsormidiophytes) ** Class Zygnemophyceae (conjugates) *** Order Zygnematales (filamentous conjugates and saccoderm desmids) *** Order Desmidiales (placoderm desmids) ** Class Coleochaetophyceae (coleochaetophytes) *** Order Coleochaetales ** Subdivision Streptophytina *** Class Charophyceae (reverts to use of GM Smith) **** Order Charales (charophytes sensu stricto) *** Class Embryophyceae (embryophytes)

Hoek, Mann and Jahns 1995

Classification of the Chlorophyta, treated as all green algae, according to Hoek, Mann and Jahns 1995. * Class Prasinophyceae (orders Mamiellales, Pseudocourfeldiales, Pyramimonadales, Chlorodendrales) * Class Chlorophyceae (orders Volvocales Tetrasporales">ncluding the Tetrasporales Chlorococcales, Chaetophorales,

) * Class Ulvophyceae (orders Codiolales,

) * Class Cladophorophyceae (order Cladophorales) * Class Bryopsidophyceae (orders

, Halimedales) * Class Dasycladophyceae (order Dasycladales) * Class Trentepohliophyceae (order Trentepohliales) * Class Pleurastrophyceae (order Pleurastrales) * ''

Incertae sedis ' () or ''problematica'' is a term used for a taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertain ...

'' (order Prasiolales) * Class Klebsormidiophyceae (orders Klebsormidiales, Coleochaetales) * Class Zygnematophyceae (order Zygnematales, Desmidiales) * Class Charophyceae (order Charales) In a note added in proof, an alternative classification is presented for the algae of the class Chlorophyceae: * Class Chlamydophyceae (orders Volvocales, Chlorococcales, Chaetophorales) * Class Oedogoniophyceae (order

) * Class Chlorophyceae (order

)

Bold and Wynne 1985

Classification of the Chlorophyta and Charophyta according to Bold and Wynne 1985. * Chlorophyta, Chlorophyceae (16 orders) ** Volvocales ** Tetrasporales ** Chlorococcales **

** Ulotrichales **

** Chaetophorales ** Trentepohliales **

** Cladophorales ** Acrosiphoniales ** Caulerpales ** Siphonocladales ** Dasycladales ** Zygnematales *

, Charophyceae (1 order) ** Charales

Mattox & Stewart 1984

Classification of the Chlorophyta according to Mattox & Stewart 1984: * Micromonadophyceae (similar to Prasinophyceae; Tetraselmidiales transferred to Pleurastrophyceae) * Charophyceae Rabenhorst ** Chlorokybales ** Klebsormidiales ** Zygnematales ** Coleochaetales ** Charales * Ulvophyceae * Pleurastrophyceae ** Tetraselmidiales ** Pleurastrales * Chlorophyceae Wille in Warming **

** Volvocales ** Chlorococcales **

** Chaetophorales **

Fott 1971

Classification of the Chlorophyta according to Fott 1971. *Class Chlorophyceae :*Order Volvocales :*Order Tetrasporales :*Order Chlorococcales :*Order Ulotrichales ::*Suborder Chlorosarcineae ::*Suborder Ulotrichineae ::*Suborder Oedogoniineae ::*Suborder Chaetophorineae :*Order Siphonocladales :*Order

*Class Conjugatophyceae *Class Charophyceae

Round 1971

Classification of the Chlorophyta and related algae according to Round 1971. * "

" ** Euglenophyta ** Prasinophyta **

** Chlorophyta ***

Zygnemaphyceae Zygnematophyceae (or Conjugatophyceae) is a class of green algae in the paraphylum streptophyte algae, also referred to as Charophyta, consisting of more than 4000 described species. It contains five orders: the Spirogloeales, the Serritaeniales, ...

(= Conjugatophyceae; orders Mesotaeniales, Zygnematales, Gonatozygales, Desmidiales) *** Oedogoniophyceae (order

) *** Bryopsidophyceae **** Hemisiphoniidae (orders Cladophorales,

, Acrosiphoniales **** Cystosiphoniidae (orders Dasycladales, Siphonocladales, Chlorochytriales) **** Eusiphoniidae (orders Derbesiales, Codiales, Caulerpales, Dichotomosiphonales, Phyllosiphonales) *** Chlorophyceae **** orders

, Volvocales, Polyblepharidales, Tetrasporales, Chlorodendrales,

, Chlorococcales **** orders Ulotrichales, Codiolales,

, Prasiolales, Cylindrocapsales, Microsporales **** orders Chaetophorales, Coleochaetales, Trentepohliales, Pleurococcales, Ulvellales

Smith 1938

Classification of the Chlorophyta according to Smith 1938: *Class 1. Chlorophyceae ::*Order 1. Volvocales ::::*Family 1. Chlamydomonadaceae ::::*Family 2. Volvocaceae ::*Order 2. Tetrasporales ::*Order 3. Ulotrichales ::::*Family 1. Ulotrichaceae ::::*Family 2.

Microsporaceae Microsporaceae are a family of green algae in the class Chlorophyceae.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 ...

::::*Family 3. Cylindrocapsaceae ::::*Family 4.

Chaetophoraceae Chaetophoraceae is a family of green algae in the order Chaetophorales. Genera * ''Arthrochaete'' * '' Caespitella'' * ''Cedercreutziella'' * ''Chaetomnion'' * ''Chaetonemopsis'' * '' Chaetophora'' * '' Chloroclonium'' * '' Chlorofilum'' * ' ...

::::*Family 5. Protococcaceae ::::*Family 6.

Coleochaetaceae Coleochaetaceae is a family of algae. It is the only family in the Coleochaetales, an order of parenchymous charophyte algae, that includes some of the closest multicellular relatives of land plants. They questionably include the fossil genus ...

::::*Family 7.

Trentepohliaceae Trentepohliaceae are a family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of ...

::*Order 4.

::::*Family 1. Ulvaceae ::::*Family 2 Schizomeridaceae ::*Order 5. Schizogoniales ::::*Family Schizogoniaceae ::*Order 6. Cladophorales ::::*Family 1. Cladophoraceae ::::*Family 2. Sphaeropleaceae ::*Order 7.

::::*Family Oedogoniaceae ::*Order 8. Zygnematales ::::*Family 1. Zygnemataceae ::::*Family 2. Mesotaeniaceae ::::*Family 3.

Desmidiaceae The Desmidiaceae are one of four families of charophyte green algae in the order Desmidiales (desmids).See the NCBIbr>webpage on Desmidiaceae Data extracted from the Genera Genera accepted by AlgaeBase were: *'' Actinodontum'' – 3 spe ...

::*Order 9. Chlorococcales ::::*Family 1.

Chlorococcaceae Chlorococcaceae is a family of green algae, in the order Chlamydomonadales. List of genera * ''Apodochloris'' * ''Bracteacoccus'' * ''Chlorococcopsis'' * ''Chlorococcum'' * ''Chlorohippotes'' * ''Chlorotetraedron'' * ''Closteridium'' * ''Cocco ...

::::*Family 2. Endosphaeraceae ::::*Family 3. Characiaceae ::::*Family 4.

Protosiphonaceae Protosiphonaceae is a family of chlorophyte green algae, in the order Chlamydomonadales. Genera , AlgaeBase AlgaeBase is a global species database of information on all groups of algae, both marine and freshwater, as well as sea-grass. Hi ...

::::*Family 5. Hydrodictyaceae ::::*Family 6. Oöcystaceae ::::*Family 7.

Scenedesmaceae Scenedesmaceae is a family of green algae in the order Sphaeropleales. ''Scenedesmus'' algae are commonly found in freshwater plankton. The former family Coelastraceae is considered a synonym of Scenedesmaceae. Genera Genera in this family ...

::*Order 10. Siphonales ::::*Family 1. Bryopsidaceae ::::*Family 2. Caulerpaceae ::::*Family 3. Halicystaceae ::::*Family 4. Codiaceae ::::*Family 5.

Derbesiaceae Derbesiaceae are 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 (Embryophytes) ...

::::*Family 6. Vaucheriaceae ::::*Family 7. Phyllosiphonaceae ::*Order 11. Siphonocladiales ::::*Family 1. Valoniaceae ::::*Family 2.

Dasycladaceae The Dasycladaceae is one of the two extant families of green algae of the order Dasycladales. When found in Palaeozoic limestones, they typically indicate depositional depth of less than 5m.See the NCBIbr>webpage on Dasycladaceae Data extract ...

*Class 2. Charophyceae ::*Order Charales ::::*Family

Characeae Characeae is a family of freshwater green algae in the order Charales, commonly known as stoneworts. They are also known as brittleworts or skunkweed, from the fragility of their lime-encrusted stems, and from the foul odor these produce when step ...

Research and discoveries

In February 2020, the fossilized remains of green algae, named ''Proterocladus antiquus'' were discovered in the northern province of Liaoning, China. At around a billion years old, it is believed to be one of the oldest examples of a multicellular chlorophyte.

Ecology

Classifications

Phylogeny

Leliaert ''et al''. 2012

Pombert ''et al''. 2005

Lewis & McCourt 2004

Hoek, Mann and Jahns 1995

Bold and Wynne 1985

Mattox & Stewart 1984

Fott 1971

Round 1971

Smith 1938

Research and discoveries

References

Further reading