The Xanthophyta or Heterokontae are commonly known as yellow-green algae include only one class Xanthophyceae. This division has close relationship with. Xanthophyta (yellow-green algae) A division of algae in which the chloroplasts are yellow-green and which form motile cells with 1 long, forward-directed tinsel. Xanthophyta: Xanthophyta, division or phylum of algae commonly known as yellow-green algae.
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As an increasing number of species were examined, the separate division Xanthophyta was created for the following characters they possess: Asexual reproduction by means of multi-flagellate zoospores whose flagella are distributed throughout the entire body—coenozoospores.
This page was last edited on 30 Julyat If you prefer to suggest your own revision of the article, you can go to edit mode requires login. The filament and its xanthophytq grow by terminal elongation. The oogonia are single or in groups, producing single egg, which is fertilized in place and develops thick walls to form an oospore.
Thank you for your feedback. You can learn more about this divksion in the related articles below. Copeland treated the group as order Vaucheriacea: Xivision shape of the aerial portion is considerably influenced by environmental conditions.
One of the outstanding features of the Xanthophyta is the presence of xanthohpyta cells bearing two flagella of unequal length. See also Photosynthetic microorganisms; Protists.
Sexual reproduction is of frequent occurrence in all species of Vaucheria but less frequent in those species growing in flowing water. When exposed to drought the protoplasmic contents of the vesicle migrate into the rhizoids and divide to form thick-walled globose to ellipsoid coenocysts also known as cysts, which either germinate directly or produce zoospores Fig.
The usual food reserve is oil. Then, copy xanthiphyta paste the text into your bibliography or works cited list. The chromatophores lack pyrenoids. Print this article Print all entries for this topic Cite this article.
A large number of nuclei and chloroplasts along with cytoplasm stream into swollen tip which is cut off by a cross-wall differentiating the zoosporangium from the rest of the filament Fig.
Biology Notes on Xanthophyta | Algae
Xanthophyta synthesize chlorophyll a and smaller amounts of chlorophyll c, instead of the chlorophyll b of plants; and the cellular structure usually have multiple chloroplasts without nucleomorphs.
The antheridia are cylindrical, generally curved, producing many small biflagellate anterozoids. Learn More in these related Britannica articles: Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.
Attachment of the filament to the substratum is by a hapteron-like structure provided with colourless branched outgrowths known as rhizoids Fig.
Biology Notes on Xanthophyta | Algae
Botrydiales Mischococcales Tribonematales Vaucheriales. Xanthophuta, Cambridge University Press, Cambridge, . Filamentous species may be either siphonous or coenocytic. Other Xanthophyceae Classes are Tribonema, whose structure consists of unbranched filaments; Botrydiopsis, such as the divixion Botrydium with several thalli, each thallus formed by a large aerial vesicle and rhizoidal filaments, found in damp soil; Olisthodiscus, such as the species Ophiocytium with cylindrical and elongated multinucleated cells and multiple chloroplasts.
The contents of the oogonium form a single large spherical egg, or ovum laden with much food.
Gustav Fischer Verlag, Stuttgart, pp. Except in the siphonaceous forms each vegetative cell is uninucleate. Modern Language Association http: Xanthophyta A phylum of mostly freshwater organisms of the kingdom Protoctista, traditionally known as yellow- green algaethat possess carotenoid pigments including xanthinswhich are responsible for their colour, in addition to chlorophylls.
Considering the simple structure of the plant body, the sexual reproduction is of fairly complicated nature. Xanthophyceae Allorge, emend. Plants are filamentous, irregularly or dichotomously branched coenocytic.
The protoplasm divides into innumerable uninucleate protoplasts. Most live in fresh water, but some are found in marine and soil habitats.
Plant body of unicellular multinucleate vesicular, globose or dichotomously branched aerial portion and a colourless rhizoidal portion; discoid chromatophores; asexual reproduction by biflagellate zoospores, aplanospores or resting spores; sexual reproduction isogamous.
Sexual reproduction is oogamous. Yellow-green algae Examples of xanthophytes repair the unequal flagella in the cells Scientific classification Domain: In spite of divisiom own dislikeness, Fritsch placed Vaucheria in the family Vaucheriaceae under the xanthophyha Siphonales belonging to the Chlorophyceae.
Bigyromonadea Bicosoecea Sagenista Labyrinthulomycetes Eogyrea.
Asexual reproduction in most species is by zoospores with a few exceptional cases where aplanospores are formed for asexual reproduction.
The species now placed in the Xanthophyceae were formerly included in the Chlorophyceae.
Because of the presence of significant amounts of chlorophyll a, Xanthophyceae species are easily mistaken for green algae. The aerial vesicular or lobed portion is covered with a relatively tough wall chiefly of cellulose, within which there is a thin, peripheral layer of cytoplasm containing many xantohphyta lenticular or fusiform plastids; oil droplets; and leucosin granules.
The method of liberation of zoospores from the mother cell is not definitely known, but it appears that it is accomplished by a gelatinization of apical portion in the vesicular wall Fig. Wikipedia articles needing page number citations from October Articles with ‘species’ microformats All articles with unsourced statements Articles with unsourced xanthophhyta from December Allorge,xanthopjyta emend.
The central portion of the filament is occupied by a large vacuole; the cytoplasm is in a thin, peripheral layer continuous along its entire length. Food reserve is oil.