Spirodela – Chi Spirodela

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

    Spirodela

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    Spirodela
    SpirodelaPolyrhiza.jpg  Spirodela - Chi Spirodela 220px SpirodelaPolyrhiza
    Spirodela polyrrhiza
    Scientific classification
    Kingdom: Plantae
    (unranked): Angiosperms
    (unranked): Monocots
    Order: Alismatales
    Family: Araceae
    Subfamily: Lemnoideae
    Tribe: Lemneae
    Genus: Spirodela
    Schleid. 1839
    Synonyms[1]
    Landoltia Les & D.J.Crawford

    Spirodela is a genus of aquatic plant, one of several genera containing plants commonly called duckweed. Spirodela species are members of the Araceae under the APG II system. They were formerly members of the Lemnaceae.[2][3]

    Spirodela species are free-floating thalli; two to five plants may remain connected to each other. Plants are green, but may have a red or brown underside. Multiple roots (seven to 12) emerge from each thallus. Spirodela is larger (10 mm) than Lemna (2–5 mm, one root per thallus).[4]

    Certain species of Spirodela overwinter as turions, a dormant form that lacks air pockets, so sinks to the bottom of the pond. In spring, turions rise to the surface and germinate to start a new population.

    Spirodela often forms floating mats with related species, e.g. Lemna and Wolffia.

    The genus is virtually cosmopolitan in distribution.[1][4]Spirodela punctata is sometimes treated as Landoltia punctata.[5]

    Species

    1. Spirodela oligorrhiza (Kurz) Hegelm. – Africa, Australia, southern Asia
    2. Spirodela polyrrhiza (L.) Schleid. – cosmopolitan
    3. Spirodela punctata (G.Mey.) C.H.Thomps. – South America, Central America, West Indies
    4. Spirodela sichuanensis M.G.Liu & K.M.Xie – southern China

    References

    1. ^ Jump up to:ab Kew World Checklist of Selected Plant Families
    2. Jump up^ Govaerts, R. & Frodin, D.G. (2002). World Checklist and Bibliography of Araceae (and Acoraceae): 1-560. The Board of Trustees of the Royal Botanic Gardens, Kew.
    3. Jump up^ Landolt, E. (1986) Biosystematic investigations in the family of duckweeds (Lemnaceae). Vol. 2. The family of Lemnaceae – A monographic study. Part 1 of the monograph: Morphology; karyology; ecology; geographic distribution; systematic position; nomenclature; descriptions. Veröff. Geobot. Inst., Stiftung Rübel, ETH, Zurich.
    4. ^ Jump up to:ab Flora of North America
    5. Jump up^ Les, D. H. and D. J. Crawford. 1999. Landoltia (Lemnaceae), a new genus of duckweeds. Novon 9: 530-533.

    External links

    • Armstrong, W. (2005) Wayne Armstrong’s treatment of the Lemnaceae.
    • Cross, J.W. (2006). The Charms of Duckweed.
    • The Duckweed Genome Project