| Charophyta |
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| Scientific classification |
| Domain: |
Eukaryota
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| (unranked) |
Archaeplastida
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| Kingdom: |
Plantae
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| (unranked) |
Streptophyta
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| Division: |
Charophyta
Migula 1897, sensu Leliaert et al. 2012 |
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| Included groups |
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Mesostigmatophyceae
Klebsormidiophyceae
Zygnematophyceae
- Zygnematales
- Desmidiales
Charophyceae
- Charales
Coleochaetales Chlorokybophyceae
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| Excluded groups |
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Embryophyta
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Charophyta is a division of freshwater green algae.[1] The terrestrial plants, the Embryophyta emerged within Charophyta, with the class Zygnematophyceae as a sister group.[2][3][4] In some charophyte groups, such as Zygnematophyceae or conjugating green algae, flagellae are absent and sexual reproduction does not involve free-swimming flagellate sperm. Flagellate sperm, however, are found in stoneworts (Charales) and Coleochaetales, orders of parenchymatous charophytes that are the closest relatives of the land plants, where flagellate sperm are also present in all except the conifers and flowering plants.[5] Fossil stoneworts of Devonian age that are similar to those of the present day have been described from the Rhynie chert of Scotland.[6]
Contents
- 1 Classification
- 2 Description
- 2.1 Cell structure
- 2.2 Sexual reproduction
- 2.3 Vegetative propagation
- 3 References
Classification
Charophyta are complex green algae that form a sister group to the Chlorophyta and within which the Embryophyta emerged. The chlorophyte and charophyte green algae and the embryophytes or land plants form a clade called the green plants or Viridiplantae, that is united among other things by the absence of phycobilins, the presence of chlorophyll b and chlorophyll a, cellulose in the cell wall and the use of starch, stored in the plastids, as a storage polysaccharide. Unlike chlorophytes, the charophytes and embryophytes share several traits, such as the presence of certain enzymes (class I aldolase, Cu/Zn Superoxide dismutase, Glycolate Oxidase, flagellar peroxidase), lateral flagella (when present), and, in many species, the use of phragmoplasts in mitosis. [7] Thus Charophyta and Embryophyta together form the clade Streptophyta, excluding the Chlorophyta. The Charophyta sensu lato does not include all the descendents of their common ancestor with the embryophytes and as such they form a paraphyletic group i.e. the classes Chlorokybophyceae; Mesostigmatophyceae; Klebsormidiophyceae; Zygnematophyceae; Coleochaetophyceae and Chaetosphaeridiales are removed from the division.[8]
Charophytes such as Palaeonitella cranii and possibly the yet unassigned Parka decipiens[9] are present in the fossil record of the Devonian.[6] Palaeonitella differed little from some present-day stoneworts.
Description
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This section needs expansion with: examples and additional citations. You can help by adding to it. (April 2014) |
The Zygnematophyceae or, as they used to be called, Conjugatophyceae, generally possess two fairly elaborate chloroplasts in each cell, rather than many discoid ones. They reproduce asexually by the development of a septum between the two cell-halves or semi-cells (in unicellular forms, each daughter-cell develops the other semi-cell afresh) and sexually by conjugation, or the fusion of the entire cell-contents of the two conjugating cells. The saccoderm desmids and the placoderm or true desmids, unicellular or filamentous members of the Zygnematophyceae, are dominant in non-calcareous, acid waters of oligotrophic or primitive lakes (e.g. Wastwater), or in lochans, tarns and bogs, as in the West of Scotland, Eire, parts of Wales and of the Lake District.[10]
Klebsormidium, the type of the Klebsormidiophyceae, is a simple filamentous form with circular, plate-like chloroplasts, reproducing by fragmentation, by dorsiventral, biciliate swarmers and, according to Wille, a twentieth-century algologist, by aplanospores.[11] The same source states that sexual reproduction is simple and isogamous (the gametes are outwardly identical without a distinct male and female, at least to look at).
The various groups included in the Charophyta have diverse and idiosyncratic reproductive systems, sometimes with complex reproductive organs. The unique habit among the algae of protecting the overwintering zygote within the tissues of the parent gametophyte is one of several characteristics of Coleochaetales that suggest that they are a sister group to the embryophytes.[12]
The Charales or stoneworts are freshwater algae with slender green or grey stems; the grey colour of many species results from the deposition of lime on the walls, masking the green colour of the chlorophyll. The main stems are slender and branch occasionally. Lateral branchlets occur in whorls at regular intervals up the stem, they are attached by rhizoids to the substrate.[13] The reproductive organs consist of antheridia and oogonia, though the structures of these organs differ considerably from the corresponding organs in other algae. As a result of fertilization a protonema is formed, from which the sexually reproducing algae develops.
Charophytes are frequently found in hard water with dissolved calcium or magnesium carbonates. They tolerate low concentrations of salt, and are found in the inner reaches of the Baltic Sea[14] and in tropical brackish lagoons[15] but not in marine environments. The water must be still, or only slow-flowing, oligotrophic or mesotrophic and little pollution due to sewage.[citation needed]
The Charophyceae are obligate aquatic algae, growing submerged in calcareous fresh water. They are distributed throughout the world from the tropics to cold temperate zones.
Six genera are recognized:-
Chara
Lamprothamnium
Lychnothamnus
Nitella
Nitellopsis
Tolypella. [13]
Cell structure
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This section needs expansion. You can help by adding to it. (April 2014) |
There are numerous small discoid chloroplasts, which are disposed around the periphery of the cells. No pyrenoids are present. The large internodal cells are sometimes multinucleate, and their nuclei often possess large nucleoli and scanty chromatin. In these cells the cytoplasm forms only a peripheral layer with a large central vacuole. The cell walls are composed of cellulose, though there may be also a superficial layer of a more gelatinous material of unknown composition.
The storage material is starch, except in the oospore, where oil also occurs. This starch also accumulates in special storage structures, termed bulbils, which consist of rounded cells of varying size which are developed in clusters on the lower stem and root nodes. They are mainly developed when the algae are growing in fine slimy mud.
Cytoplasmic streaming was first demonstrated in the giant cells of Chara internodes by Giovanni Battista Amici, in 1818.
Sexual reproduction
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This section needs expansion. You can help by adding to it. (April 2014) |
The reproductive organs of the Charales show a high degree of specialization. The female organ is a large oval structure with an envelope of spirally arranged, bright green filaments of cells. It is termed an oogonium. The male organ is also large, bright yellow or red in colour, spherical in shape, and is usually termed an antheridium, though some workers regard it as a multiple structure rather than a single organ. The sex organs are developed in pairs from the adaxial nodal cell at the upper nodes of the primary lateral branches, the oogonium being formed above the antheridium. They are sufficiently large to be easily seen with the naked eye, especially the bright orange or red antheridium. Many species are dioecious. In others the monoecious condition is complicated by the development of the antheridium before the formation of the oogonium, thus preventing fertilization by antherozoids of the same alga. In this case the two types of sex organs usually arise from different points on the lateral branches
Vegetative propagation
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This section needs expansion. You can help by adding to it. (April 2014) |
Vegetative propagation occurs readily in the Charales. Secondary protonemata may develop even more rapidly than primary ones. Fragments of nodes, dormant cells of algae after hibernation or the basal nodes of primary rhizoids may all produce these secondary protonemata, from which fresh sexual algae can arise. It is probably this power of vegetative propagation which explains the fact that species of Characeae are generally found forming dense clonal mats in the beds of ponds or streams, covering quite large areas.
References
- ^ Lewis, Louise A.; Richard M. McCourt (2004). "Green algae and the origin of land plants" (abstract). American Journal of Botany. 91 (10): 1535–1556. doi:10.3732/ajb.91.10.1535. PMID 21652308.
- ^ "BMC Evolutionary Biology 2014, 14:23".
- ^ Wickett, Norman J.; Mirarab, Siavash; Nguyen, Nam; Warnow, Tandy; Carpenter, Eric; Matasci, Naim; Ayyampalayam, Saravanaraj; Barker, Michael S.; Burleigh, J. Gordon (2014-11-11). "Phylotranscriptomic analysis of the origin and early diversification of land plants". Proceedings of the National Academy of Sciences. 111 (45): E4859–E4868. doi:10.1073/pnas.1323926111. ISSN 0027-8424. PMC 4234587. PMID 25355905.
- ^ Vries, Jan de; Stanton, Amanda; Archibald, John M.; Gould, Sven B. (2016-02-16). "Streptophyte Terrestrialization in Light of Plastid Evolution". Trends in Plant Science. 0 (0). doi:10.1016/j.tplants.2016.01.021. ISSN 1360-1385.
- ^ Vaughn, K.C.; Renzaglia, K.S. (2006). "Structural and immunocytochemical characterization of the Ginkgo biloba L. sperm motility apparatus.". Protoplasma. 227 (2-4): 165–73. doi:10.1007/s00709-005-0141-3.
- ^ a b Kelman, R.; Feist, M.; Trewin, N.H.; Hass, H. (2003). "Charophyte algae from the Rhynie chert". Transactions of the Royal Society of Edinburgh: Earth Sciences. 94 (4): 445–455. doi:10.1017/s0263593300000808.
- ^ 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.
- ^ Tree of Life: Green plants
- ^ Hemsley, A.R. (1989). "The ultrastructure of the spores of the Devonian plant Parka decipiens". Annals of Botany. 64 (3): 359–367.
- ^ West, Fritsch, G.S., F.E. (1927). A Treatise of the British Freshwater Algae. Cambridge: Cambridge University Press.
- ^ Fritsch, F.E. (1935). The Structure and Reproduction of the Algae, vol I. Cambridge University Press. pp. 205–206.
- ^ Becker, B.; Marin, B. (2009). "Streptophyte algae and the origin of embryophytes". Annals of Botany. 103 (7): 999–1004. doi:10.1093/aob/mcp044. PMC 2707909. PMID 19273476.
- ^ a b Bryant 2007, J. The Stoneworts (Chlorophyta, Charales) in Guiry, M.D., John, D.M., Rindi, F. and McCarthy, T.K (Ed) New Survey of Clare Island Volume 6: The Freshwater and Terrestrial Algae. Royal Irish Academy. ISBN 9781904890317
- ^ Schubert, H.; Blindow, I. (2004). Charophytes of the Baltic Sea. Gantner Verlag. ISBN 3906166066.
- ^ Palma-Silva, C.; Albertoni, E.F.; Esteves, F.A. (2004). "Charophytes as nutrient and energy reservoir in a tropical coastal lagoon impacted by humans (RJ, Brazil).". Brazilian Journal of Biology. 64: 479–487. doi:10.1590/s1519-69842004000300011.
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Early land flora
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| Related links |
- Evolutionary history of plants
- Rhynie chert
- External link directory
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| The first...? |
- Vascular plant, Cooksonia
- Tree, Wattieza
- Lycopods, the Drepanophycales and the zosterophylls
- Fungus fossil, Ornatifilum
- Lichen, Spongiophyton
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| Enigmatic taxa |
- Cuticular remains: Bitelaria
- Cosmochlaina
- Nematothallus
- Orestovia
- Protosalvinia
- Spongiophyton
- Other: Pachytheca
- Prototaxites.
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| Sister taxa |
- Green algae: Charophyta, from which land plants evolved
- Chaetocladus, an early alga
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Classification of Archaeplastida / Plantae sensu lato
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- Domain
- Archaea
- Bacteria
- Eukaryota
- (Supergroup
- Plant
- Hacrobia
- Heterokont
- Alveolata
- Rhizaria
- Excavata
- Amoebozoa
- Opisthokonta
- Animal
- Fungi)
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Rhodophyta
(red algae) |
- Cyanidiophyceae
- Porphyridiophyceae
- Compsopogonophyceae
- Stylonematophyceae
- Rhodellophyceae
- Bangiophyceae
- Florideophyceae
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Glaucocystophyta
(glaucophytes) |
- Glaucocystophyceae
- Glaucocystis
- Cyanophora
- Gloeochaete
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Viridiplantae
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Chlorophyta s.s.
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- Palmophyllales
- Nephroselmidophyceae
- Prasinophyceae
- Pseudoscourfieldiales
- Mamiellophyceae
- Pyramimonadophyceae
- Scourfieldiales
- Pedinophyceae
- Chlorodendrophyceae
- UTC clade
- Ulvophyceae
- Trebouxiophyceae
- Chlorophyceae
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Streptophyta
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Charophyta s.l.
(paraphyletic) |
- Mesostigmatophyceae
- Chlorokybophyceae
- Klebsormidiophyceae
- Zygnematophyceae
- Chaetosphaeridiaceae
- Coleochaetophyceae
- Charophyceae
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Embryophyta
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Bryophytes
(paraphyletic) |
- Marchantiophyta
- Anthocerotophyta
- Bryophyta "Moss"
- †Taeniocradales
- †Horneophytopsida
- †Lyonophytales
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Tracheophyta
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paraphyletic
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- †Yarraviales
- †Rhyniophyta
- †Cooksoniales
- †Renaliaceae
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| Lycopodiophyta |
- †Zosterophyllopsida
- †Sawdoniales
- †Haskinsiaceae
- Isoetopsida
- Lycopodiopsida
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Euphyllophyta
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paraphyletic
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- †Trimerophyta
- †Cecropsidales
- †Noeggerathiopsida
- †Aneurophytopsida
- †Archaeopteridopsida
- †Protopityales
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Moniliformopses
(ferns) |
- †Ibykales
- †Cladoxylopsida
- †Stauropteridales
- †Zygopteridales
- Equisetopsida
- Psilotopsida
- Marattiopsida
- Filicopsida
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Spermatophyta
(seed plants) |
- †Axelrodiopsida
- †Arberiopsida
- †Moresnetiopsida
- †Lyginopteridopsida
- †Pachytestopsida
- †Callistophytales
- †Peltaspermopsida
- †Umkomasiales
- Pinopsida
- Cycadopsida
- Ginkgopsida
- †Phasmatocycadopsida
- †Pentoxylopsida
- †Dictyopteridiopsida
- †Cycadeoideopsida
- †Caytoniopsida
- Magnoliopsida
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See also: list of plant orders
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