Chlorophyta, a division of green algae The green algae are the large group of algae from which the embryophytes (higher plants) emerged. As such, they form a paraphyletic group, although the group including both green algae and embryophytes is monophyletic (and often just known as kingdom Plantae). The green algae include unicellular and colonial flagellates, usually but not always,[3] includes about 7,000 species There are many definitions of what kind of unit a species is . A common definition is that of a group of organisms capable of interbreeding and producing fertile offspring of both genders, and separated from other such groups with which interbreeding does not (normally) happen. Other definitions may focus on similarity of DNA or morphology. Some[4][5] of mostly aquatic An aquatic ecosystem is an ecosystem located in water bodies. Communities of organisms that are dependent on each other and on their environment live in aquatic ecosystems. The two main types of aquatic ecosystems are marine ecosystems and freshwater ecosystems photosynthetic Photosynthesis is a process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of Bacteria, but not in Archaea. Photosynthetic organisms are called photoautotrophs, since it allows them to create their own food. In plants, algae and eukaryotic A eukaryote is an organism whose cells contain complex structures enclosed within membranes. The defining membrane-bound structure that sets eukaryotic cells apart from prokaryotic cells is the nucleus, or nuclear envelope, within which the genetic material is carried. The presence of a nucleus gives eukaryotes their name, which comes from the organisms. Like the land plants The embryophytes are the most familiar group of plants. They are often called land plants because they live primarily in terrestrial habitats, in contrast with the related green algae that are primarily aquatic. The embryophytes include trees, flowers, ferns, mosses, and various other green land plants. All are complex multicellular eukaryotes (bryophytes Bryophytes are all embryophytes that are non-vascular: they have tissues and enclosed reproductive systems, but they lack vascular tissue that circulates liquids. They neither have flowers nor produce seeds, reproducing via spores. The term bryophyte comes from Greek βρύον - bryon, "tree-moss, oyster-green" + φυτόν - fyton & and tracheophytes Vascular plants are those plants that have lignified tissues for conducting water, minerals, and photosynthetic products through the plant. Vascular plants include the ferns, clubmosses, flowering plants, conifers and other gymnosperms. Scientific names for the group include Tracheophyta and Tracheobionta, but neither name is very widely used), green algae contain chlorophylls a and b, and store food as starch Starch or amylum is a polysaccharide carbohydrate consisting of a large number of glucose units joined together by glycosidic bonds. Starch is produced by all green plants as an energy store. It is the most important carbohydrate in the human diet and is contained in such staple foods as rice, wheat, maize , potatoes and cassava[4] in their plastids Plastids are major organelles found in the cells of plants and algae. Plastids are the site of manufacture and storage of important chemical compounds used by the cell. Plastids often contain pigments used in photosynthesis, and the types of pigments present can change or determine the cell's colour. They are related to the Charophyta The Charophyta are a division of green algae, including the closest relatives of the embryophyte plants. In some groups, such as conjugating green algae, flagellate cells do not occur. The latter group does engage in sexual reproduction, and motility does not involve flagella, since they are totally lacking. Flagellate cells in the form of sperm and Embryophyta (land plants), together making up the Viridiplantae Viridiplantae are a clade comprising the green algae and land plants.

The division contains both unicellular and multicellular species. While most species live in freshwater habitats Freshwater ecosystems are among the earth aquatic ecosystems. They include lakes and ponds, rivers, streams and springs, and wetlands. They can be contrasted with marine ecosystems, which have a larger salt content. Freshwater habitats can be classified by different factors, including temperature, light penetration, and vegetation and a large number in marine habitats Marine biology is the scientific study of living organisms in the ocean or other marine or brackish bodies of water. Given that in biology many phyla, families and genera have some species that live in the sea and others that live on land, marine biology classifies species based on the environment rather than on taxonomy. Marine biology differs, other species are adapted to a wide range of environments. Watermelon snow Watermelon snow, also called snow algae, is snow that is reddish or pink in color, with the slight scent of a fresh watermelon. This type of snow is common during the summer in alpine and coastal polar regions worldwide, such as the Sierra Nevada of California. Here, at altitudes of 10,000 to 12,000 feet , the temperature is cold throughout the, or Chlamydomonas nivalis, of the class Chlorophyceae, lives on summer alpine snowfields. Others live attached to rocks or woody parts of trees. Some lichens Lichens are composite organisms consisting of a symbiotic association of a fungus (the mycobiont) with a photosynthetic partner (the photobiont or phycobiont), usually either a green alga (commonly Trebouxia) or cyanobacterium (commonly Nostoc). The morphology, physiology and biochemistry of lichens are very different from those of the isolated are symbiotic relationships between fungi and green algae. Members of the Chlorophyta also form symbiotic relationships with protozoa Protozoa or Cornelius protozoans (from Greek proton proton "first" and ζῷα zoa "animals"; singular protozoon; are microorganisms classified as unicellular eukaryotes, sponges and cnidarians. All are flagellated[6] and these have an advantage of motility. Some conduct sexual reproduction which is oogamy or isogamy.

Classes

Class Prasinophyceae In taxonomy, Prasinophytes are a class of the Division Chlorophyta. These are primitive eukaryotic, marine green algae. Its best known genus is Ostreococcus , which is considered to be the smallest (ca. 0.95 μm) free-living eukaryote and which has been detected in marine samples around the world. Prasinophytes are thought to have low cellular T. A. Chr. ex Ø. Moestrup & J. Throndsen

Classification according to Hoek, Mann and Jahns 1234.[4]

Classification according to Bold and Wynne (Introduction to the Algae, Second Edition, Prentice Hall NJ)

References

  1. ^ Pascher A (1914). "Über Flagellaten und Algen". Berichte der deutsche botanischen Gesellschaft 32: 136–160.
  2. ^ Adl SM, Simpson AGB, Farmer MA, Andersen RA, Anderson OR, Barta JR, Bowser SS, Brugerolle G, Fensome RA, Fredericq S, James TY, Karpov S, Kugrens P, Krug J, Lane CE, Lewis LA, Lodge J, Lynn DH, Mann DG, McCourt RM, Mendoza L, Moestrup Ø, Mozley-Standridge SE, Nerad TA, Shearer CA, Smirnov AV, Speigel FW, Taylor MFJR (2005). "The new higher level classification of eukaryotes with emphasis on the taxonomy of protists". Journal of Eukaryotic Microbiology 52: 399–451. doi The Digital Object Identifier System is a managed system for persistent identification of content-related entities on digital networks. These entities may be content items (digital files, physical objects, abstract works), or any related entities in a content transaction (e.g. licenses, parties, etc.). "DOI" is sometimes used to mean the:10.1111/j.1550-7408.2005.00053.x.
  3. ^ a b Guiry, M.D. & Guiry, G.M. (2007). "Phylum: Chlorophyta taxonomy browser". AlgaeBase version 4.2 World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org/browse/taxonomy/?id=4307. Retrieved 2007-09-23.
  4. ^ a b c Hoek, C. van den, Mann, D.G. and Jahns, H.M. 1995. Algae An Introduction to Phycology. Cambridge University Press, Cambridge. ISBN 0 521 30419 9
  5. ^ "Major Algae Phyla - Table - MSN Encarta". Archived from the original on 2009-10-31. http://www.webcitation.org/5kwQwljiE.
  6. ^ Kapraun DF (April 2007). "Nuclear DNA content estimates in green algal lineages: chlorophyta and streptophyta". Ann. Bot. 99 (4): 677–701. doi The Digital Object Identifier System is a managed system for persistent identification of content-related entities on digital networks. These entities may be content items (digital files, physical objects, abstract works), or any related entities in a content transaction (e.g. licenses, parties, etc.). "DOI" is sometimes used to mean the:10.1093/aob/mcl294. PMID A PMID is a unique number assigned to each PubMed citation of life sciences and biomedical scientific journal articles. The related Pubmed Central archive may additionally assign a separate number, a PMCID (PubMed Central Identifier), normally written with a PMC prefix 17272304. http://aob.oxfordjournals.org/cgi/pmidlookup?view=long&pmid=17272304.

Further reading

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Classification of Archaeplastida The Archaeplastida are a major line of eukaryotes, comprising the land plants, green and red algae, and a small group called the glaucophytes. All of these organisms have plastids surrounded by two membranes, suggesting they developed directly from endosymbiotic cyanobacteria. In all other groups, plastids are surrounded by three or four membranes, / Plantae sensu lato Plants are living organisms belonging to the kingdom Plantae. They include familiar organisms such as trees, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The scientific study of plants, known as botany, has identified about 350,000 extant species of plants, defined as seed plants, bryophytes, ferns and fern allies. As of 2004,
Rhodophyta The red algae (or Rhodophyta, pronounced /roʊˈdɒfɨtə, ˌroʊdəˈfaɪtə/, from Greek: ῥόδον = rose + φυτόν (phyton) = plant, thus red plant) are one of the oldest groups of eukaryotic algae, and also one of the largest, with about 5,000–6,000 species of mostly multicellular, marine algae, including many notable seaweeds. Other Rhodophyceae · Bangiophyceae Bangiophyceae was a class of red algae; it has since been merged with the Floridophyceae to form the Rhodophyceae. The Bangiophyceae, as defined traditionally, are paraphyletic.. Their taxonomic identification has been difficult because of a lack of distinct morphological features, and the presumed morphological plasticity of the species · Florideophyceae Florideophyceae was a class of red algae. It is now merged with the Bangiaceae into the Rhodophyceae. They were once thought to be the only algae to bear pit connections, but these have since been found in the filamentous stage of the Bangiacae · Goniotrichales · Stylonematophyceae
Glaucocystophyceae The glaucophytes, also known as glaucocystophytes or glaucocystids, are a small group of freshwater microscopic algae. Together with the red algae and Viridiplantae they form the Archaeplastida. However, the relationships between the red algae, green algae and glaucophytes are unclear, in large part due to limited study of the glaucophytes Glaucocystis · Cyanophora · Gloeochaete
Viridiplantae Viridiplantae are a clade comprising the green algae and land plants/ Plantae sensu stricto
Chlorophyta/GA The green algae are the large group of algae from which the embryophytes (higher plants) emerged. As such, they form a paraphyletic group, although the group including both green algae and embryophytes is monophyletic (and often just known as kingdom Plantae). The green algae include unicellular and colonial flagellates, usually but not always Prasinophyceae In taxonomy, Prasinophytes are a class of the Division Chlorophyta. These are primitive eukaryotic, marine green algae. Its best known genus is Ostreococcus , which is considered to be the smallest (ca. 0.95 μm) free-living eukaryote and which has been detected in marine samples around the world. Prasinophytes are thought to have low cellular UTC clade: Ulvophyceae · Trebouxiophyceae In taxonomy, the Trebouxiophyceae are a class of green algae, in the division Chlorophyta · Chlorophyceae The Chlorophyceae are one of the classes of green algae, distinguished mainly on the basis of ultrastructural morphology. For example the chlorophycean CW clade, and chlorophycean DO clade, are defined by the arrangement of their flagella. Members of the CW clade have flagella that are displaced in a "clockwise" direction eg
Streptophyta Streptophytina is formally a subdivision or subphylum which contains two classes: Charophyceae, containing the Charales order (Charophytes sensu stricto); and Embryophyceae, which contains the embryophytes (land plants, bryophytes, and vascular plants)
Charophyta The Charophyta are a division of green algae, including the closest relatives of the embryophyte plants. In some groups, such as conjugating green algae, flagellate cells do not occur. The latter group does engage in sexual reproduction, and motility does not involve flagella, since they are totally lacking. Flagellate cells in the form of sperm/GA The green algae are the large group of algae from which the embryophytes (higher plants) emerged. As such, they form a paraphyletic group, although the group including both green algae and embryophytes is monophyletic (and often just known as kingdom Plantae). The green algae include unicellular and colonial flagellates, usually but not always
Chlorokybophyceae Chlorokybales
Klebsormidiophyceae The Klebsormidiales are an order containing three genera of charophyte green alga forming multicellular, non-branching filaments Klebsormidiales The Klebsormidiales are an order containing three genera of charophyte green alga forming multicellular, non-branching filaments
Zygnematophyceae Zygnematophyceae is an order of green algae. It contains two orders: Zygnematales and Desmidiales Desmidiales Desmids are an order of green algae, comprising around 40 genera and 5,000 to 6,000 species, found mostly but not exclusively in fresh water. Most are unicellular, and are divided into two compartments separated by a narrow bridge or isthmus. Desmids assume a variety of highly symmetrical and generally attractive shapes, which provide the basis · Zygnematales The Zygnematales (Greek: ζυγός + νήμα (nēma) (nom.), νήματος (nēmatos) (gen.)), also called the Conjugales, are an order of green algae, comprising several thousand different species in genera such as the well-known Zygnema and Spirogyra. All the members of this group develop into unbranched filaments, one cell thick, which grow
Charophyceae Charophyceae is a taxon of green algae whose exact rank is the matter of some current debate. Some botanists recommend expanding the existing plant kingdom to include charophyceans and chlorophytes while others consider Charophyceae to be a class within either the divisions Chlorophyta, Streptophytina, or Streptophyta. Other systematists classify Charales
Coleochaetophyceae Coleochaetales
Embryophyta/ Plantae sensu strictissimo
Bryophytes (non-vascular) Marchantiophyta · Anthocerotophyta · Bryophyta "Moss" · Horneophytopsida
Tracheophyta
Lycopodiophyta Isoetopsida (Isoetales, Selaginellales) · Lycopodiopsida (Lycopodiales)
Euphyllophyta Moniliformopses (Equisetopsida, Filicopsida, Psilotopsida) Spermatophyta: Gymnosperm (Pinophyta, Cycadophyta, Ginkgophyta, Gnetophyta) · Magnoliophyta
See also: list of plant orders
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