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Yellow-green algae or xanthophytes are an important group of heterokont algae. Most live in freshwater, but some are found in marine and soil habitats. They vary from single-celled flagellates to simple colonial and filamentous forms. Xanthophyte chloroplasts contain the photosynthetic pigments Chlorophyll ''a'', Chlorophyll ''c'', β-Carotene, and the carotenoid diadinoxanthin. Unlike other heterokonts, their chloroplasts do not contain fucoxanthin, which accounts for their lighter colour. Its storage polysaccharide is chrysolaminarin.〔 Xanthophyte cell walls are produced of cellulose and hemicellulose.〔 They appear to be the closest relatives of the brown algae. == Classifications == The species now placed in Xanthophyceae were formerly included in the Chlorophyceae.〔Chapman, V. J. ''An Introduction to the Study of Algae''. University Press, Cambridge; The Macmillan Company, New York, 1941, p. 18, ().〕 In 1899, Luther created the group Heterokontae for green algae with unequal flagella. Pascher (1914) included the Heterokontae in Chrysophyta. In 1930, Allorge renamed the group as Xanthophyceae. The monadoid (unicellular flagellates) and also sometimes the amoeboid species have been included by some authors in Protozoa or in Protista,〔Copeland (1956), p. 63〕 as order Heterochloridina (e.g., Doflein and Reichenow, 1927-1929〔Doflein, F. & Reichenow, E. 1927-1929. ''Lehrbuch der Protozoenkunde'', 5th ed, G. Fischer, Jena. 1262 p.〕), as class Xanthomonadina, with orders Heterochloridea and Rhizochloridea (e.g., Deflandre, 1956〔Deflandre, G. (1952). In: Grassé, P.-P. (Ed.). ''Traité de Zoologie''. Vol. 1, fasc. 1. Phylogénie. Protozoaries: Generalités, Flagellés. Masson et Cie, Paris. pp. 212, 217, 220.〕), as order Heterochlorida (e.g., Hall, 1953,〔Hall, R.P., 1953. ''Protozoology''. Prentice-Hall, New York, (),〕 Honigberg et al., 1964), as order Heteromonadida (e.g., Leedale, 1983), or as subclass Heterochloridia (e.g., Puytorac et al., 1987〔Puytorac, P. de, Grain, J., Mignot, J.P. ''Précis de protistologie''. Lubrecht & Cramer Ltd, 1987. 581 p.〕). These groups are called ambiregnal protists, as names for these have been published under either or both of the ICZN and the ICN. Xanthophyceae have been divided into the following four orders in some classification systems: *Order Botrydiales * * ''Asterosiphon'' * * ''Botrydium'' *Order Mischococcales * * ''Botrydiopsis'' * * ''Botryochloris'' * * ''Bumilleriopsis'' * * ''Chlorellidium'' * * ''Mischococcus'' * * ''Monodus'' * * ''Ophiocytium'' * * ''Pleurochloris'' * * ''Pseudobumilleriopsis'' * * ''Sphaerosorus'' *Order Tribonematales Pascher * * ''Bumilleria'' * * ''Heterococcus'' * * ''Heterothrix'' * * ''Tribonema'' * * ''Xanthonema'' *Order Vaucheriales Nägeli ex Bohlin〔Christensen, T. 1987. ''Seaweeds of the British Isles.'' Volume 4 Tribophyceae (Xanthophyceae). British Museum (Natural History), London ISBN 0-565-00980-X〕 * * Vaucheria 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Yellow-green algae」の詳細全文を読む スポンサード リンク
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