Spirodela
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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.<ref>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.</ref><ref>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.</ref>
Description
Spirodela species are free-floating plants that have their stem transformed into leaf-like structures called fronds; each plant is represented by a frond with roots, therefore they do not have leaves.<ref name=":0">Template:Cite book</ref> Two to five plants may remain connected to each other.
Plants are green, but may turn red due to the presence of anthocyanin.<ref name=":0" /> Multiple roots (5 to 20, depending on the species) emerge from each frond. Spirodela is larger (Template:Convert) than Lemna (Template:Convert – Template:Convert, with one root per frond).<ref name="r" />
Certain species of Spirodela overwinter as turions, dormant starchy shoots<ref name=":0" /> that lack air pockets, which sink to the bottom of the water. In spring, turions rise to the surface and germinate.
Spirodela often forms floating mats with related species (e.g. Lemna and Wolffia).
The genus is virtually cosmopolitan in distribution.<ref name="yuk">Kew World Checklist of Selected Plant FamiliesTemplate:Dead link</ref><ref name="r">Flora of North America</ref>
Species
There are currently 2 recognized species in this genus:<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>
- Spirodela polyrhiza (L.) Schleid. - cosmopolitan
- Spirodela intermedia W.Koch
References
External links
- Armstrong, W. (2005) Wayne Armstrong's treatment of the Lemnaceae Template:Webarchive.
- Cross, J.W. (2006). The Charms of Duckweed.
- The Duckweed Genome Project