Spirodela

Spirodela is a genus of aquatic plants, 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
Spirodela polyrrhiza
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Order: Alismatales
Family: Araceae
Subfamily: Lemnoideae
Genus: Spirodela
Schleid. 1839
Synonyms[1]

Landoltia Les & D.J.Crawford

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 (0.39 in)) than Lemna (2 mm (0.079 in) – 5 mm (0.20 in), 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. Kew World Checklist of Selected Plant Families
  2. 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. 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. Flora of North America
  5. Les, D. H. and D. J. Crawford. 1999. Landoltia (Lemnaceae), a new genus of duckweeds. Novon 9: 530-533.


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