Water-meal is one of the duckweeds in the family Lemnaceae that
contains some 38 species of the smallest and simplest flowering
plants. The plant itself averages 1/42” long and 1/85” wide
or about the size of one candy sprinkle. It can weigh about 1/190,000
of an ounce, equivalent to two grains of table salt. They are very
hard to see! Imagine if you tried to fill a thimble with them,
it is estimated that you would need some 5000 plants!
Each Wolffia flower consists of a single pistil and stamen; it
also produces the world’s smallest fruit, called a utricle.
The plant is found in quiet freshwater lakes or marshes with species
worldwide. Since the plants have no roots, they can easily float
on the surface of the water, where they resemble cornmeal. Water-meal
is sometimes used in cold-water aquaria since it is easy to propagate.
David. Encyclopedia of aquarium & pond fish. New
York, Dorling Kindersley, 2005. 400 p.
Wayne. P. Duckweeds, California’s smallest wildflowers.
Fremontia, v. 10, Oct. 1982: 16-22.
Edwin Horace. A monograph of Lemnaceae. Urbana, University
of Illinois Press, 1965. 118 p.
William G. Wolffia in Canada. Canadian field naturalist,
v.71, Jan./Mar. 1957: 10-16.
Ernestine. Pond plants. Chicago, Heinemann Library, c1999.
32 p. (Juvenile literature).
family. In Crow, Garrett E., and C. Barre Hellquist.
Aquatic and wetland plants of northeastern North
America. Madison, University of Wisconsin Press, c2000. v. 2,
Albert. Flowering of Lemnaceae. Bulletin of the Torrey
Botanical Club, v. 56, Oct. 1929: 351-358.
Paul, William Spira, and William Journey. Duckweed
aquaculture: a new aquatic farming system for developing
countries. Washington, World Bank, c1993. 76 p.
more print resources...
Search on "Duckweeds," "Aquatic
plants," or "Pond plants"
in the Library of Congress Online
Texas Cooperative Extension site, Dept. of Wildlife & Fisheries
Sciences, Texas A & M University.
(Wolffia columbiana Karsten.) Northern Prairie Wildlife Research Center, USGS site.
in duckweed. US
Fish and Wildlife Service, Panther National Wildlife Refuge Web
watermeal, and filamentous algae cover the water's surface near
Maynard, Massachusetts. USGS Massachusetts - Rhode Island Water
Science Center Web site.