The Charms of Duckweed
The family of duckweeds (botanically, the Lemnaceae) are the
smallest flowering plants. These plants grow floating in
still or slow-moving fresh water around
the globe, except in the coldest regions. The growth of these
high-protein plants can be extremely rapid. Lemna is one of the best
known of this group and has been the subject of much
research. Researchers have recently published a duckweed genome.
Researchers are using these plants to study basic plant development, plant biochemistry,
photosynthesis, the toxicity
of hazardous substances, and much more. Genetic engineers
are cloning duckweed genes and
modifying duckweeds to inexpensively produce pharmaceuticals.
Environmental scientists are using duckweeds to remove unwanted
substances from water. Aquaculturalists find them an
source for fish farming.
To learn more about these fascinating plants, next read the botanical facts, or view some duckweed illustrations. Read about cloning.
|We wish to honor the memory of the foremost duckweed scholar, Professor Elias Landolt, who died April 1, 2013. [ Published Obituary ]|
Duckweed-related organizations and conferences
Research and applications of duckweeds are promoted by
two organizations, The International Lemna Association (ILA)
and the International Steering Committee on Duckweed
Research and Applications (ISCDRA).
An international team of researchers led by Joachim Messing has published an interpretive study of the Spirodela genome. The DNA sequence yields insights into how duckweeds are adapted for rapid vegetative growth and why their anatomy mimics the juvenile stages of other plants. The research was published in Nature Communications on 19 February 2014.
The researchers discovered Spirodela has fewer protein genes than other flowering plants, about 20,000, or 28 percent less than Arabidopsis, and 50 percent less than rice. Also, Spirodela has more genes that repress, and fewer genes that promote, the transition to the adult phase stages of plant growth. Spirodela has up to 32 copies of a gene for regulatory RNA, miRNA 156, which promotes the juvenile stage and inhibits the adult phase.
[ read more ]
Genes and gene clusters common to a duckweed and other flowering plants.
Duckweed on Lake Maracaibo, VenezuelaDuckweed growth on this natural lake has been a persistent issue since the early 2000s.
Venezuela struggled to remove aquatic plant faster than it spread over nation's largest lake
Thursday, 17 June 2004 by Alexandra Olson, Associated Press
CARACAS, Venezuela 52; Efforts to remove an aquatic weed from Venezuela's largest lake are barely keeping up with its growth, the environment minister said Wednesday. The green plant, known as duckweed or lemna, covers about 12 percent of Lake Maracaibo's 13,500-square kilometer (5,400-square mile) surface, said Ana Elisa Osorio. The lake in western Venezuela is one of South America's largest bodies of water and is an important oil-producing region.... [ read more ]
A study of the causes of the 2004 invasion of Lake Maracaibo by duckweed and proposals for future action was published in July of that year [ link ]. The Venezuelan government subsequently implemented mechanical skimming to remove this vegetation. By September 2004, 75% of the duckweed had been removed by the mechanical skimmers.
However, the duckweed continues to be a problem on the lake. Satellite imaging for the period 2005-2011 showed an average duckweed coverage of about 1.5% of the almost 13,000 km2 lake, ranging from 0.5% to almost 7% in extreme years. [
At times, over 18% of the lake has been covered by duckweed - See more at: http://www.eosnap.com/lakes/issues-for-lake-maracaibo-venezuela/#sthash.B8uHPcsW.dpuf[ link ]
Above: NASA image of Lake
Maracaibos. Duckweed (Lemna obscura) can be
seen in large swirls across the lake surface.
Philadelphia Inquirer Photo, 08/17/1999
|Read how duckweeds can take over lakes
Left: Duckweeds do not normally grow in
rivers, but a drought in the summer of 1999 reduced the
flow of water into the Schuylkill River in Philadelphia,
Pennsylvania. The reduced flow increased the levels
of nutrients and allowed a duckweed bloom to accumulate in
the channel. After this picture was taken, the
duckweeds gradually were washed away by the current of the
|Notes to students
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Revised: March 14, 2015