Wolffia

Wolffia
Each speck is an individual plant (on human fingers, for scale).
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Monocots
Order:	Alismatales
Family:	Araceae
Subfamily:	Lemnoideae
Genus:	Wolffia Schleid.
Species
9-11, see text

Close-up of two different duckweeds: Spirodela polyrrhiza and Wolffia globosa: The very tiny Wolffia plants are under 2 millimetres (0.079 in) long.

Wolffia is a genus of nine to 11 species which include the smallest flowering plants on Earth. Commonly called watermeal or duckweed, these aquatic plants resemble specks of cornmeal floating on the water. Wolffia species are free-floating thalli, green or yellow-green, and without roots. The flower is produced in a depression on the top surface of the plant body. It has one stamen and one pistil. Individuals often float together in pairs or form floating mats with related plants, such as Lemna and Spirodela species. Most species have a very wide distribution across several continents. Wolffia species are composed of about 40% protein on a dry-matter basis, about the same as the soybean, making them a potential high-protein human food source. They have historically been collected from the water and eaten as a vegetable in much of Asia.

Selected species

• Wolffia angusta
• Wolffia arrhiza
• Wolffia australiana
• Wolffia borealis
• Wolffia brasiliensis
• Wolffia columbiana
• Wolffia cylindracea
• Wolffia elongata
• Wolffia globosa
• Wolffia microscopica
• Wolffia neglecta

An 1885 illustration of Wolffia arrhiza

Further reading

• Treatment:Lemnaoideae, Wayne P. Armstrong, from The Jepson Manual
• Wolffia Horkel ex Schleid, a USDA Plants Profile
• The Duckweed Genome Project from Rutgers University
• Armstrong, W. (2005). "Wayne Armstrong's treatment of the Lemnaceae". Palomar Community College District. Retrieved 2011-05-01.
• Cross, J.W. (September 6, 2008). "The Charms of Duckweed". Missouri Botanical Garden. Retrieved 2011-05-01.
• Landolt, E. (1986) Biosystematic investigations in the family of duckweeds (Lemnaceae). Vol. 2. The family of Lemnaceae - A monographic study. Part 1 of the monograph: Morphology; karyology; ecology; geographic distribution; systematic position; nomenclature; descriptions. Veröff. Geobot. Inst., Stiftung Rübel, ETH, Zurich.