Viridiplantae Classification Essay

Green plants include all organisms commonly known as green algae and land plants, including liverworts, mosses, ferns and other nonseed plants, and seed plants.


Green plants as defined here includes a broad assemblage of photosynthetic organisms that all contain chlorophylls a and b, store their photosynthetic products as starch inside the double-membrane-bounded chloroplasts in which it is produced, and have cell walls made of cellulose (Raven et al., 1992). In this group are several thousand species of what are classically considered green algae, plus several hundred thousand land plants.

Discussion of Phylogenetic Relationships

There are two major lineages of green plants. One consists of most of what have been classically considered "green algae"--mostly microscopic freshwater forms and large seaweeds. The other lineage contains several groups of "green algae" that are more closely related to land plants. Because these two lineages are monophyletic, they have been placed in a single monophyletic group called green plants, or, in technical parlance, the subkingdom Chlorobionta (Bremer, 1985).

The groups of the primary "green algal" lineage included here (Prasinophytes, Chlorophyceae, Trebouxiophyceae, and Ulvophyceae) represent a synthesis of the most recent classifications based primarily on ultrastructure of motile cells (when present) and analysis of molecular data (small subunit rDNA) Melkonian and Surek, 1995; Friedl, 1995). The groups represent classes of green algae, except for the "Prasinophytes," which, although erected as a class (Prasinophyceae), is apparently a paraphyletic, basal radiation within the "green algal" lineage (Melkonian, 1990; Friedl, 1995; Melkonian and Surek, 1995). The name for the sister taxon to the Chlorophyceae used here (class Trebouxiophyceae) is has also been referred to as the order Microthmaniales (Melkonian and Surek, 1995); recent studies of small-subunit rDNA sequences led Friedl (1995) to raise the group to class level.

The other main lineage of green plants has been called the Streptophytes (Bremer, 1985), which consists of some organisms traditionally considered green algae plus the more familiar green plants found mostly on land. This lineage contains green algae that most textbooks include in the Class Charophyceae, but some members of this class are in fact more closely related to higher plants than to other members of the class (Mattox and Stewart, 1984; Mishler and Churchill, 1985; McCourt, 1995; Melkonian and Surek, 1995). Specifically, Chara and related algae (Order Charales) and Coleochaete and related algae (Order Coleochaetales) are probably the closest living "green algal" relatives of land plants. Ultrastructural and morphological studies were the first to support the relationship of these ordersof green algae to land plants (embryophytes) (Pickett-Heaps, 1975; Mishler and Churchill, 1985; Graham et al., 1991). The orders were all placed in the class Charophyceae (Mattox and Stewart,1984) and retained within the green algae (Division Chlorophyta in the classical sense [Bold andWynne, 1985]. Recent analyses suggest that the Charophyceae is a paraphyletic group, and therefore the orders originally circumscribed within it have been placed within the Streptophyta (Bremer, 1985).

Later molecular studies (reviews in McCourt, 1995 and Melkonian and Surek, 1995) largelyconfirmed this close relationship, and confirmed what the ultrastructural and morphological data had first suggested: that the Charophyceae is a paraphyletic assemblage. Specifically, the Charales and Coleochaetales are most closely related to land plants (Chapman and Buchheim, 1991; Ragan et al. 1993; Surek et al., 1993; Bhattacharya et al., 1994). The Charales/Coleochaetales/Embryophyte clade is shown as unresolved because morphological and molecular studies to date have not fully resolved which of the green algae is the sister taxon ofland plants (McCourt 1995; Melkonian and Surek, 1995).


Bhattacharya, D., Surek, B., Rüsing, M., Damberger, S., and Melkonian, M. (1994) Group I introns are inherited through common ancestry in the nuclear-encoded rRNA of Zygnematales (Charophyceae). Proc. Natl. Acad. Sci. USA 91: 9916-20.

Bold, H. C. & Wynne, M. J. (1985) Introduction to the Algae. 2nd ed., Prentice-Hall, Inc., Englewood Cliffs, New Jersey, 720 pp.

Bremer, K. (1985) Summary of green plant phylogeny and classification. Cladistics 1:369-385.

Friedl, T. (1995) Inferring taxonomic positions and testing genus level assignments in coccoid green lichen algae: A phylogenetic analysis of 18S ribosomal RNA sequences from Dictyochloropsis reticulata and from members of the genus Myrmecia (Chlorophyta, Trebouxiophyceae Cl. Nov.). J. Phycol. 31:632-639.

Graham, L. E., Delwiche, C. F. & Mishler, B. D. 1991. Phylogenetic connections between the 'Green Algae' and the 'Bryophytes.' Adv. Bryol., 4, 213-244.

Mattox, K. R. & Stewart, K. D. (1984) Classification of the green algae: A concept based on comparative cytology. In: Systematics of the Green Algae. Irvine, D.E.G. & John, D.M. [Eds.] Academic Press, London, pp. 29-72.

McCourt, R. M. (1995) Green algal phylogeny. Trends in Ecology and Evolution 10:159-163.

Melkonian, M. (1990) Phylum Chlorophyta: Introduction to the Chlorophyta. In: Handbook of Protoctista. Margulis, L., Corliss, J. O., Melkonian, M., and Chapman, D. J., eds. pp. 597-599. Jones and Bartlett Publishers, Boston. [Note: This chapter is followed by several others on the "green algae."]

Melkonian, M. and Surek, B. (1995) Phylogeny of the Chlorophyta: Congruence between ultrastructural and molecular evidence. Bull. Soc. Zool. Fr. 120: 191-208.

Mishler, B. D. & Churchill, S. P. (1985) Transition to a land flora: phylogenetic relationships of the green algae and bryophytes. Cladistics 1:305-28.

Pickett-Heaps, J. D. (1975) Green Algae: Structure, Reproduction and Evolution in Selected Genera. Sinauer Associates, Inc., Sunderland, Massachusetts, 606 pp.

Raven, P. H., Evert, R. H., Eichhorn, S. E. (1992) Biology of Plants. 5th Edition. Worth Publishers, New York.

Surek, B., Beemelmanns, U., Melkonian, M. & Bhattacharya, D. 1993. Ribosomal RNA sequence comparisons demonstrate an evolutionary relationship between Zygnematales and charophytes. Pl. Syst. Evol., 191, 171-81.

About This Page

Academy of Natural Sciences of Drexel University

R. L. Chapman
Louisiana State University, Baton Rouge, Louisiana, USA

Mark Buchheim
University of Tulsa, Oklahoma, USA

Brent D. Mishler
University of California, Berkeley, California, USA

Correspondence regarding this page should be directed to Richard M. McCourt at

Page copyright © 2009

Citing this page:

McCourt, Richard M., R. L. Chapman, Mark Buchheim, and Brent D. Mishler. 1996. Green plants. Version 01 January 1996 (under construction). The Tree of Life Web Project,

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

An assortment of thallophyte Viridiplantae in a rock pool, Taiwan
Scientific classification
Cavalier-Smith, 1981
  • Plantae Copeland, 1938, 1956[1][2]
  • Euchlorophyta Whittaker, 1969[3]
  • Chlorophyta sensu van den Hoek & Jahns, 1978[4]
  • 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[5]
  • 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 (literally "green plants")[6] are a clade of eukaryotic organisms made up of the green algae, which are primarily aquatic, and the land plants (embryophytes), which emerged within them.[7][8][9] Green algae traditionally excludes the land plants, rendering them a paraphyletic group. They 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. More than 350,000 species of Viridiplantae exist.[10]

In some classification systems, the group has been treated as a kingdom,[11] 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 with green chlorophyll. They rejected the name Viridiplantae on the grounds that some of the species are not plants, as understood traditionally.[12] The Viridiplantae are made up of two clades: Chlorophyta and Streptophyta.[13] Together with Rhodophyta and glaucophytes, Viridiplantae are thought to belong to a larger clade called Archaeplastida or Primoplantae.

A taxonomic evaluation of eukaryotes based on myosin distribution showed the Viridiplantae lost class-I myosins.[14]

Phylogeny and classification[edit]

Leliaert et al. 2012[edit]

Simplified phylogeny of the Viridiplantae, according to Leliaert et al. 2012.[15]


Below is a consensus reconstruction of green algal relationships, mainly based on molecular data.[17][18][19][20][21][22][23]


  1. ^Copeland, H.F. (1938). "The kingdoms of organisms". Quart. Rev. Biol. 13: 383–420. 
  2. ^Copeland, H. F. (1956). The Classification of Lower Organisms. Palo Alto: Pacific Books, p. 6 [1].
  3. ^Whittaker, R. H. (1969). "New concepts of kingdoms or organisms"(PDF). Science. 163 (3863): 150–160. doi:10.1126/science.163.3863.150. PMID 5762760. 
  4. ^van den Hoek, C. & Jahns, H. M. (1978). Algen. Einführung in die Phykologie. Georg Thieme Verlag, Stuttgart.
  5. ^Cavalier-Smith, T. (1981). "Eukaryote kingdoms: Seven or nine?". BioSystems. 14 (3–4): 461–481. doi:10.1016/0303-2647(81)90050-2. PMID 7337818. 
  6. ^T. Cavalier-Smith (1981). "Eukaryote Kingdoms: Seven or Nine?". BioSystems. 14 (3–4): 461–481. doi:10.1016/0303-2647(81)90050-2. PMID 7337818. 
  7. ^Cocquyt E, Verbruggen H, Leliaert F, Zechman FW, Sabbe K, De Clerck O (2009). "Gain and loss of elongation factor genes in green algae". BMC Evol. Biol. 9: 39. doi:10.1186/1471-2148-9-39. PMC 2652445. PMID 19216746. 
  8. ^Becker B (2007). "Function and evolution of the vacuolar compartment in green algae and land plants (Viridiplantae)". Int. Rev. Cytol. International Review of Cytology. 264: 1–24. doi:10.1016/S0074-7696(07)64001-7. ISBN 9780123742636. PMID 17964920. 
  9. ^Kim E, Graham LE (2008). Redfield, Rosemary Jeanne, ed. "EEF2 analysis challenges the monophyly of Archaeplastida and Chromalveolata". PLoS ONE. 3 (7): e2621. doi:10.1371/journal.pone.0002621. PMC 2440802. PMID 18612431. 
  10. ^Smith SA, Beaulieu JM, Donoghue MJ (2009). "Mega-phylogeny approach for comparative biology: an alternative to supertree and supermatrix approaches". BMC Evol. Biol. 9: 37. doi:10.1186/1471-2148-9-37. PMC 2645364. PMID 19210768. 
  11. ^"Viridiplantae". Retrieved 2009-03-08. 
  12. ^Adl, Sina M.; et al. (2005), "The New Higher Level Classification of Eukaryotes with Emphasis on the Taxonomy of Protists", Journal of Eukaryotic Microbiology, 52 (5): 399–451, doi:10.1111/j.1550-7408.2005.00053.x, PMID 16248873 
  13. ^Simon A, Glöckner G, Felder M, Melkonian M, Becker B (2006). "EST analysis of the scaly green flagellate Mesostigma viride (Streptophyta): implications for the evolution of green plants (Viridiplantae)". BMC Plant Biol. 6: 2. doi:10.1186/1471-2229-6-2. PMC 1413533. PMID 16476162. 
  14. ^Odronitz F, Kollmar M (2007). "Drawing the tree of eukaryotic life based on the analysis of 2,269 manually annotated myosins from 328 species". Genome Biol. 8 (9): R196. doi:10.1186/gb-2007-8-9-r196. PMC 2375034. PMID 17877792. 
  15. ^Leliaert, F., Smith, D.R., Moreau, H., Herron, M.D., Verbruggen, H., Delwiche, C.F. & De Clerck, O. (2012). "Phylogeny and molecular evolution of the green algae"(PDF). Critical Reviews in Plant Sciences. 31: 1–46. doi:10.1080/07352689.2011.615705. 
  16. ^Marin, B (2012). "Nested in the Chlorellales or Independent Class? Phylogeny and Classification of the Pedinophyceae (Viridiplantae) Revealed by Molecular Phylogenetic Analyses of Complete Nuclear and Plastid-encoded rRNA Operons". Protist. 163: 778–805. doi:10.1016/j.protis.2011.11.004. PMID 22192529. 
  17. ^Lewis, L. A & R. M. McCourt (2004). "Green algae and the origin of land plants". American Journal of Botany. 91 (10): 1535–1556. doi:10.3732/ajb.91.10.1535. PMID 21652308. 
  18. ^Leliaert, Frederik; Smith, David R.; Moreau, Hervé; Herron, Matthew D.; Verbruggen, Heroen; Delwiche, Charles F.; De Clerck, Olivier (2012). "Phylogeny and Molecular Evolution of the Green Algae"(PDF). Critical Reviews in Plant Sciences. 31: 1–46. doi:10.1080/07352689.2011.615705. 
  19. ^Marin, Birger (2012). "Nested in the Chlorellales or Independent Class? Phylogeny and Classification of the Pedinophyceae (Viridiplantae) Revealed by Molecular Phylogenetic Analyses of Complete Nuclear and Plastid-encoded rRNA Operons". Protist. 163: 778–805. doi:10.1016/j.protis.2011.11.004. PMID 22192529. 
  20. ^Laurin-Lemay, Simon; Brinkmann, Henner; Philippe, Hervé (2012). "Origin of land plants revisited in the light of sequence contamination and missing data". Current Biology. 22: R593–R594. doi:10.1016/j.cub.2012.06.013. PMID 22877776. 
  21. ^"BMC Evolutionary Biology 2014, 14:23". 
  22. ^Leliaert, Frederik; Tronholm, Ana; Lemieux, Claude; Turmel, Monique; DePriest, Michael S.; Bhattacharya, Debashish; Karol, Kenneth G.; Fredericq, Suzanne; Zechman, Frederick W. (2016-05-09). "Chloroplast phylogenomic analyses reveal the deepest-branching lineage of the Chlorophyta, Palmophyllophyceae class. nov". Scientific Reports. 6: 25367. doi:10.1038/srep25367. ISSN 2045-2322. PMC 4860620. PMID 27157793. 
  23. ^Adl, Sina M.; Simpson, Alastair G. B.; Lane, Christopher E.; Lukeš, Julius; Bass, David; Bowser, Samuel S.; Brown, Matthew W.; Burki, Fabien; Dunthorn, Micah (2012-09-01). "The Revised Classification of Eukaryotes". Journal of Eukaryotic Microbiology. 59 (5): 429–514. doi:10.1111/j.1550-7408.2012.00644.x. ISSN 1550-7408. 


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