Viridiplantae

For an explanation of very similar terms, see plant and green algae.

Viridiplantae (lit. 'green plants')^[6] is a clade of around 450,000–500,000 species of eukaryotic organisms, most of which obtain their energy by photosynthesis. The green plants are chloroplast-bearing autotrophs that play important primary production roles in both terrestrial and aquatic ecosystems.^[7] They include green algae, which are primarily aquatic, and the land plants (embryophytes), which emerged within freshwater green algae.^[8][9][10] Green algae traditionally excludes the land plants, rendering them a paraphyletic group, however it is cladistically accurate to think of land plants as a special clade of green algae that evolved to thrive on dry land.^[11] Since the realization that the embryophytes emerged from within the green algae, some authors are starting to include them.^{[11][12][13][14][15]}

Viridiplantae Temporal range: Stenian[1] – Present Pha. Proterozoic Archean Had.
An assortment of thallophyte Viridiplantae in a rock pool, Taiwan
Scientific classification
Domain:	Eukaryota
Clade:	Diaphoretickes
Clade:	CAM
Clade:	Archaeplastida
Clade:	Viridiplantae Cavalier-Smith, 1981
Subgroups
Prasinodermophyta Chlorophyta Streptophyta Mesostigmatophyceae Chlorokybophyceae Klebsormidiophyceae Charophyceae Coleochaetophyceae Zygnematophyceae Embryophyta
Synonyms
Plantae, Copeland, 1938, 1956[2][3] Euchlorophyta Whittaker, 1969[4] Chlorophyta sensu van den Hoek & Jahns, 1978[5] Chlorobionta Jeffrey 1982, emend. Bremer 1985, emend. Lewis and McCourt 2004 Chlorobiota Kendrick and Crane 1997 Chloroplastida Adl et al., 2005 Viridiplantae Cavalier-Smith 1981[6] Phyta Barkley 1939 emed. Holt & Uidica 2007 Cormophyta Endlicher, 1836 Cormobionta Rothmaler, 1948 Euplanta Barkley, 1949 Telomobionta Takhtajan, 1964 Embryobionta Cronquist et al., 1966 Metaphyta Whittaker, 1969

Viridiplantae species all have cells with cellulose in their cell walls, and primary chloroplasts derived from endosymbiosis with cyanobacteria that contain chlorophylls a and b and lack phycobilins. Corroborating this, a basal phagotroph Archaeplastida group has been found in the Rhodelphydia.^[16] In some classification systems, the group has been treated as a kingdom,^[17] under various names, e.g. Viridiplantae, Chlorobionta, or simply Plantae, the latter expanding the traditional plant kingdom to include the green algae. Adl et al., who produced a classification for all eukaryotes in 2005, introduced the name Chloroplastida for this group, reflecting the group having primary chloroplasts. They rejected the name Viridiplantae on the grounds that some of the species are not plants as understood traditionally.^[18] Together with Rhodophyta and glaucophytes, Viridiplantae are thought to belong to a larger clade called Archaeplastida or Primoplantae.

Evolution

Taxonomy

Leliaert et al, 2012 propose the following simplified taxonomy of the Viridiplantae.^[19]

• Viridiplantae
  • Chlorophyta
    • core chlorophytes
      • Ulvophyceae
        • Cladophorales
        • Dasycladales
        • Bryopsidales
        • Trentepohliales
        • Ulvales-Ulotrichales
        • Oltmannsiellopsidales
      • Chlorophyceae
        • Oedogoniales
        • Chaetophorales
        • Chaetopeltidales
        • Chlamydomonadales
        • Sphaeropleales
      • Trebouxiophyceae
        • Chlorellales
        • Oocystaceae
        • Microthamniales
        • Trebouxiales
        • Prasiola clade
      • Chlorodendrophyceae
        • Chlorodendrales
      • Pedinophyceae^[20]
    • prasinophytes (paraphyletic)
      • Pyramimonadales
      • Mamiellophyceae
      • Pycnococcaceae
      • Nephroselmidophyceae
      • Prasinococcales
      • Palmophyllales
• Streptophyta
  • Charophytes
    • Mesostigmatophyceae
      • Mesostigmatales
      • Chlorokybales
    • Klebsormidiophyceae
    • Phragmoplastophyta
      • Charophyceae
      • Coleochaetophyceae
      • Zygnematophyceae
      • Embryophyta (land plants)

Phylogeny

In 2019, a phylogeny based on genomes and transcriptomes from 1,153 plant species was proposed.^[21] The placing of algal groups is supported by phylogenies based on genomes from the Mesostigmatophyceae and Chlorokybophyceae that have since been sequenced. Both the "chlorophyte algae" and the "streptophyte algae" are treated as paraphyletic (vertical bars beside phylogenetic tree diagram) in this analysis.^[22][23] The classification of Bryophyta is supported both by Puttick et al. 2018,^[24] and by phylogenies involving the hornwort genomes that have also since been sequenced.^[25][26]

Archaeplastida	Rhodophyta Glaucophyta Viridiplantae Prasinodermophyta Chlorophyta   Mesostigmatophyceae Chlorokybophyceae Spirotaenia Klebsormidiales Chara Coleochaetales Zygnematophyceae Embryophytes Bryophytes Hornworts Liverworts Mosses Lycophytes Ferns Spermatophytes Gymnosperms Angiosperms (seed plants) (land plants) (green plants)	"chlorophyte algae" "streptophyte algae"

Ancestrally, the green algae were flagellates.^[19]

References

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2. Copeland, Herbert F. (1938). "The kingdoms of organisms". The Quarterly Review of Biology. 13 (4): 383–420. doi:10.1086/394568. S2CID 84634277.
3. Copeland, H.F. (1956). The Classification of Lower Organisms. Palo Alto: Pacific Books. p. 6.
4. Whittaker, R.H. (January 1969). "New concepts of kingdoms or organisms. Evolutionary relations are better represented by new classifications than by the traditional two kingdoms" (PDF). Science. 163 (3863): 150–60. CiteSeerX 10.1.1.403.5430. doi:10.1126/science.163.3863.150. PMID 5762760. Archived from the original (PDF) on 2017-11-17. Retrieved 2015-01-31.
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18. Adl, Sina M.; Simpson, Alastair G.B.; Farmer, Mark A.; et al. (2005). "The new higher level classification of eukaryotes with emphasis on the taxonomy of protists". The Journal of Eukaryotic Microbiology. 52 (5): 399–451. doi:10.1111/j.1550-7408.2005.00053.x. PMID 16248873. S2CID 8060916.
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21. Leebens-Mack, M.; Barker, M.; Carpenter, E.; et al. (2019). "One thousand plant transcriptomes and the phylogenomics of green plants". Nature. 574 (7780): 679–685. doi:10.1038/s41586-019-1693-2. PMC 6872490. PMID 31645766.
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