Spirodela

Spirodela
	Spirodela polyrrhiza
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Monocots
Order:	Alismatales
Family:	Araceae
Subfamily:	Lemnoideae
Genus:	Spirodela; Schleid. 1839
Synonyms
	Landoltia Les & D.J.Crawford

Spirodela is a genus of

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 (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

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

References

^ ^a ^b Kew World Checklist of Selected Plant Families
^ 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.
^ 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.
^ ^a ^b Flora of North America
^ Les, D. H. and D. J. Crawford. 1999. Landoltia (Lemnaceae), a new genus of duckweeds. Novon 9: 530-533.