Wolffia is a genus of 9 to 11 species which include the smallest flowering plant

Flowering plant

The flowering plants , also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants. Angiosperms are seed-producing plants like the gymnosperms and can be distinguished from the gymnosperms by a series of synapomorphies...

s on Earth. Commonly called watermeal or duckweed, these aquatic plant

Aquatic plant

Aquatic plants are plants that have adapted to living in aquatic environments. They are also referred to as hydrophytes or aquatic macrophytes. These plants require special adaptations for living submerged in water, or at the water's surface. Aquatic plants can only grow in water or in soil that is...

s resemble specks of cornmeal

Cornmeal

Cornmeal is flour ground from dried maize or American corn. It is a common staple food, and is ground to fine, medium, and coarse consistencies. In the United States, the finely ground cornmeal is also referred to as cornflour. However, the word cornflour denotes cornstarch in recipes from the...

 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

Stamen

The stamen is the pollen producing reproductive organ of a flower...

 and one pistil. Individuals often float together in pairs or form floating mats with related plants, such as Lemna

Lemna

Lemna is a genus of free-floating aquatic plants from the duckweed family. These rapidly-growing plants have found uses as a model system for studies in community ecology, basic plant biology, in ecotoxicology, in production of biopharmaceuticals, and as a source of animal feeds for agriculture...

and Spirodela

Spirodela

Spirodela is a genus of aquatic plant. It is one of several genera containing plants commonly called duckweed. Spirodela species are members of the Araceae under the APG II system. They were formerly members of the Lemnaceae....

species. Most species have a very wide distribution across several continents. Wolffia species are composed of about 40% protein, about the same as the soybean

Soybean

The soybean or soya bean is a species of legume native to East Asia, widely grown for its edible bean which has numerous uses...

, 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 arrhiza
  Wolffia arrhiza is a species of flowering plant known by the common names spotless watermeal and rootless duckweed, belonging to the Araceae, a family rich in water-loving species, such as Arum and Pistia. It is the smallest vascular plant on Earth...
  
  
• Wolffia australiana
• Wolffia borealis
  Wolffia borealis
  Wolffia borealis is a species of flowering plant known by the common name northern watermeal. It is native to North America including sections of Canada and the United States. It grows in mats on the surface of calm water bodies, such as ponds. It is a very tiny plant with no leaves, stems, or roots...
  
  
• Wolffia brasiliensis
  Wolffia brasiliensis
  Wolffia brasiliensis is a species of flowering plant known by the common name Brazilian watermeal. It is native to North and South America, where it grows in mats on the surface of calm water bodies, such as ponds. It is a very tiny plant with no leaves, stems, or roots...
  
  
• Wolffia columbiana
  Wolffia columbiana
  Wolffia columbiana is a perennial aquatic plant in the Duckweed family . This plant is distributed widely throughout North, Central, and South America, and also occurs in Curaçao....
  
  
• Wolffia cylindracea
• Wolffia elongata
• Wolffia globosa
  Wolffia globosa
  Wolffia globosa is a species of flowering plant known by the common name Asian watermeal. It is native to Asia and it is found in parts of the Americas, where it may be native or naturalized. It grows in mats on the surface of calm water bodies, such as ponds. It is a very tiny plant with no...
  
  
• Wolffia microscopica
• Wolffia neglecta