The Charms of Duckweed

An introduction to the smallest flowering plants

Leopard Frog
                  in Duckweed - Click to see more images.

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 inexpensive feed source for fish farming.  [ More topics

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 conferencesILA logo

Research and applications of duckweeds are promoted by two organizations, The International Lemna Association and the International Steering Committee on Duckweed Research and Applications (ISCDRA). 

The International Lemna Association (ILA) is a non-profit organization whose mission is to promote the development of commercially-viable markets for renewable and sustainable products derived from duckweed. Its membership consists of people, companies, and organizations across the value chain.  ISCDRA organizes biennial International conferences on duckweed Duckweed Research and Applications and publishes a newsletter which serves as an informal means of  distributing information to the duckweed community.  [ read more ]



A Duckweed Genome

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 shared by Spirodela and other plants.
Genes and gene clusters common to a duckweed and other flowering plants.

Duckweed on Lake Maracaibo, Venezuela

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.  [ read more ]

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. [ reference ]

NASA
                      Image

Above: NASA image of Lake Maracaibos.  Duckweed (Lemna obscura) can be seen in large swirls across the lake surface.
[ NASA article ]
[ high resolution image, GeoTIFF file (2 MB, TIFF, 888x888). ]


More Topics:
[ Why do duckweeds have roots? ] [ Duckweed Habitat ] [ How to Grow Duckweeds ] [ How to control excess duckweed ] [ Biotech Products from Duckweed ] [ Herbivores and Pathogens [ duckweed and phytoremediation books ]

Rowing
                through duckweed on the Schuylkill River.
Philadelphia Inquirer Photo, 08/17/1999
Read how duckweeds can take over lakes and rivers.

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 river.


Notes to students and teachers:
  • If you have performed or sponsored a successful science project or class demonstration using duckweeds, please let me know about it.  I am interested in publishing selected projects on this web site.
  • Please report errors, typos or omissions.  I want to make this site as accurate and helpful as I can.  If you have suggestions for additions or changes in organization, they are also welcome.
  • Selected by the sciLINKS program, a service of National Science Teachers Association. Copyright 2001.
  • Books on duckweeds and other aquatic plants are available.

Selected by the sciLINKS program


 
 
 
 
 
 
 
 
 
 
 
 
 
 



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Revised:  September 27, 2014