Spirodela
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 Spirodela polyrhiza
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Spirodela intermedia |
Spirodela is a genus of aquatic plant, commonly called duckweed. Spirodela species are members of the Araceae under the APG II system. They were formerly members of the Lemnaceae.
Spirodela species are free-floating thalii, 2-5 plants may remain connected to each other. Plants are green, but may have a red or brown underside. Multiple roots (7 to 12) emerge from each thallus. Spirodela is larger (10 mm) than Landoltia (usually 3-6 mm with 2-3 roots per thallus) and Lemna (2-5 mm, one root per thallus).
Certain species of Spirodela overwinter as turions, a dormant form that lacks air pockets and so sinks to the bottom of the pond. In spring turions rise to the surface and germinate to start a new population.
Spirodela often froms floating mats with related species, e.g. Lemna and Wolffia.
[edit] References and external links
- Armstrong, W. (2005) Wayne Armstrong's treatment of the Lemnaceae. [1].
- Cross, J.W. (2006). The Charms of Duckweed. [2]
- 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.
