||Rapid Growth||Duckweed Habitat|
Duckweed in full bloom
|Close-up of flowering Lemna
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.Taxonomy / Key.
(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),
Lemna (mid-sized) and Wolffia (smallest),
scale in millimeters.
Photo by Gerald Carr, University of Hawaii.
A Formal Botanical Description
in industrial-strength botanical language is available by L.
Watson and M.J. Dallwitz.
"Habit and leaf form. Much reduced, aquatic herbs. Plants of very peculiar vegetative form; thalloid (thallus small to minute, globular, flat or linear, with one (Wolffioideae) or two (Lemnoïdeae) budding pouches, raphides present with mucilage cells in Lemnoïdeae only, xylem without vesses, phloem transfer cells lacking at least in Lemna). Leaves absent. Plants with roots (usually, in Lemnoïdeae), or rootless (Wolffioïdeae). Annual. Hydrophytic; free floating. ."
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.
Evolution: Where did the duckweeds come
from? How are the different species related?
Learn more firsthand. If you
are interested in duckweeds, try
some experiments yourself. They are easily grown in small containers
outside or in the laboratory.
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Last revised: February 22, 2014