||Rapid Growth||Controlling Duckweed
Duckweed in full bloom
of flowering Lemna gibba.
Lemna flowers consist of two stamens (pollen bearing organs) and a single style (pollen receptive organ).
This plant has two leaves and a single root extending at the bottom of the picture. The flower is at the top of the photograph. It consists of two stamens (pollen bearing organs) and a single style (pollen receptive organ). At its top, each stamen bears an anther where the pollen develops. The stigma, which will receive the pollen in fertilization, is the cup-shaped body atop the stigma. The ovary is at the base of the style.
Photo from Wayne Armstrong's Web site, Key to the Lemnaceae Of North America.
Although duckweeds can set seed and produce fruit like other flowering plants, they mostly reproduce vegetatively. The leaves of duckweeds commonly are called fronds, but are not considered fronds by strict botanical definition. Unlike the ordinary leaves of most plants, each duckweed frond contains buds from which more fronds may grow. These buds are hidden from view in pouches along the center axis of older fronds. As they grow, new fronds emerge through slits in the side of their parent fronds. Until they mature, daughter fronds may remain attached to the parent frond. See and read more on duckweed anatomy.
Formal Botanical Description in industrial-strength
language is available by L. Watson and M.J. Dallwitz.
Another formal description from a course, Taxonomy of Vascular Plants, at Cornell University.
Botanical drawings from "Flora von Deutschland Österreich und der Schweiz" by Prof. Dr. Otto Wilhelm Thomé, 1885, reprinted by Kurt Stüber, Max-Planck-Institut für Züchtungsforschung, Cologne, Germany.
|Plant body (frond) has one or more roots.
(click on link for drawings and photos)
|Two or more roots:||Spirodela and Landoltia|
|Plant body has no roots|
|Flattened plant body:||Wolffiella|
|Oval-shaped plant body, less than 1 mm:||Wolffia|
Three duckweeds together: Spirodela (largest),
(mid-sized) and Wolffia (smallest), scale in
Photo by Gerald Carr, University of Hawaii.
Duckweed Evolution: Where did the duckweeds come from? How are the different species related?
Recent Taxonomic Research (not available on-line).
Les, D.H., Landolt, E., Crawford, D.J. (1997) Systematics of the Lemnaceae (Duckweeds): inferences from micromolecular and morphological data. Plant Systematics and Evolution 204: 161-177.
Les, D. H. & D. J. Crawford. (1999) "Landoltia (Lemnaceae), a new genus of duckweeds." Novon 9: 530-533.
Les, Donald H., Crawford, Daniel J., Landolt, Elias, Gabel, John D., Kimball, Rebecca T. (2002) "Phylogeny and Systematics of Lemnaceae, the Duckweed Family" Systematic Botany 27: 221-240.
Learn more firsthand. If you are
in duckweeds, try some experiments
yourself. They are easily grown
in small containers outside or in the laboratory.
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Last revised: August 5, 2006