Green plantsRichard M. McCourt, R. L. Chapman, Mark Buchheim, and Brent D. Mishler
This tree diagram shows the relationships between several groups of organisms.
The root of the current tree connects the organisms featured in this tree to their containing group and the rest of the Tree of Life. The basal branching point in the tree represents the ancestor of the other groups in the tree. This ancestor diversified over time into several descendent subgroups, which are represented as internal nodes and terminal taxa to the right.
You can click on the root to travel down the Tree of Life all the way to the root of all Life, and you can click on the names of descendent subgroups to travel up the Tree of Life all the way to individual species.close box
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 orders of 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 and Wynne, 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) largely confirmed 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 of land 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.
- the green tree of life.
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- Deep Gene. An NSF funded research project geared towards the integration of plant phyogenetics and plant genomics.
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- Photo Essays at the Missouri Botanical Garden. Travel with botanists as they collect in different parts of the world, see some of the plants they collect, and learn more about the countries they collect in.
- Plant Cell Imaging. Visualizing live plant cells using fluorescent molecular tags combined with laser scanning confocal microscopy (LSCM). Carnegie Institution of Washington.
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R. L. Chapman
Louisiana State University, Baton Rouge, Louisiana, USA
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
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Citing this page:
McCourt, Richard M., R. L. Chapman, Mark Buchheim, and Brent D. Mishler. 1996. Green plants. Version 01 January 1996 (under construction). http://tolweb.org/Green_plants/2382/1996.01.01 in The Tree of Life Web Project, http://tolweb.org/