Riccia – Chi Riccia

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    Riccia - Chi Riccia Riccia aquaticum genus freshwater aquarium plants 600 x 600
     
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    Species from this Genus – Các cây trong Chi này:

    Riccia

    From Wikipedia, the free encyclopedia
     
     
    This article is about the plant Riccia. For the Italian “comune”, see Riccia, Molise.
    Riccia
    Riccia huebeneriana Lindenb. Kohatakegoke.JPG  Riccia - Chi Riccia 220px Riccia huebeneriana Lindenb
    Riccia huebeneriana
    Scientific classification
    Kingdom: Plantae
    Division: Marchantiophyta
    Class: Marchantiopsida
    Order: Marchantiales
    Family: Ricciaceae
    Genus: Riccia
    L., 1753
    Species
    • R. atlantica
    • R. beyrichiana
    • R. bifurca
    • R. canaliculata
    • R. cavernosa
    • R. crozalsii
    • R. crystallina
    • R. fluitans
    • R. gangetica
    • R. glauca
    • R. huebeneriana
    • R. nigrella
    • R. rhenana
    • R. sorocarpa
    • R. subbifurca

    Riccia is a genus of liverworts in the order Marchantiales.[1]

    The plants are small and thallose, that is not differentiated into root, stem and leaf. Depending on species, the thallus may be strap-shaped and about 0.5 to 4 mm wide with dichotomous branches or may form rosettes or hemirosettes up to 3cm in diameter, that may be gregarious and form intricate mats.[1][2]

    The thallus is dorsiventrally differentiated. Its upper (dorsal) surface is green and chlorophyll-bearing, with a mid-dorsal longitudinal sulcus (furrow or groove). Air pores occasionally break through the dorsal surface, giving the thallus a dimpled appearance.[3]

    The lower (ventral) surface has a mid-ventral ridge bearing multicellular scales that originate as a single row but normally separate into two rows as the thallus widens. The scales are multicellular and hyaline (glassy) in appearance, or violet due to the pigment anthocyanin.[1]

    Rhizoids are nearly lacking in aquatic forms, but there are usually numerous unicellular rhizoids of two types on the ventral surface.[1] One type is called smooth and the other type is the pegged or tuberculated rhizoids; these help in anchorage and absorption. The inner surface of the smooth rhizoids is smooth while that of the tuberculate rhizoid will have internal cell wall projections.

    Plants are usually monoicous, and sexual reproduction is by antheridia and archegonia. Asexual reproduction occurs by spores, by fragmentation of the rosettes, and by formation of apical tubers. Spores are large (45 to 200 µ) and formed in tetrads.[1]

    One of the more than 100 species in this genus is the “slender riccia” (Riccia fluitans), which grows on damp soil or, less commonly, floating in ponds,[3]and is sometimes used in aquariums.

    References

    1. ^ Jump up to:abcde Schuster, Rudolf M. (1992). The Hepaticae and Anthocerotae of North America. VI. Chicago: Field Museum of Natural History. pp. 421–440. ISBN 0-914868-21-7.
    2. Jump up^ Atherton, Ian; Bosanquet, Sam; Lawley, Mark, eds. (2010). Mosses and liverworts of Britain and Ireland: a field guide. UK: British Bryological Society. p. 261-270. ISBN 978-0956131010.
    3. ^ Jump up to:ab MacVicar, Symers M. 1971. The student’s handbook of British hepatics, p. 12-13. Hitchen Whelden & Wesley, Ltd.; Authorized reprint of the 1926 edition published by Sumfield & Day, Ltd.