The world’s smallest flowering plant is the watermeal, or Wolffia globosa. Found all over the planet, this bright green oval plant is about the size of a grain of rice!

Wolffia is the smallest genus of the aquatic plants known as duckweeds, which are part of the family Lemnaceae. Usually found floating in masses in freshwater lakes, streams, and marshes, they are rootless and rarely flower, mostly reproducing when the main plant, or “mother frond,” grows a new segment, or “daughter frond,” from one end. Wolffia also produce the world’s smallest fruit.

According to the International Lemna Association (ILA), this tiny plant and its relatives could help our planet in a big way. The nonprofit organization is dedicated to promoting duckweed as a fast-growing, sustainable crop with a wide variety of uses. Duckweed is eaten by ducks and other aquatic birds, along with certain fish such as tilapia, but it can also be used in the diets of chickens, pigs, and cattle.

According to John W. Cross, author of the website The Charms of Duckweed, these plants quickly absorb the minerals they need for growth, as well as other organic nutrients, from the water they’re floating in. Duckweeds are especially good at taking phosphates and nitrogen out of water — two substances that need to be removed during sewage treatment and from farming runoff. Yet when grown on sewage or animal waste, duckweeds normally don’t retain toxins, so they can be used as feed or to fertilize crops.

Wolffia globosa with the larger leaved Spirodela polyrhiza Photo: Eric Guinther

The ILA website says that duckweed has other potential commercial applications: it could be a source of renewable and sustainable fuel to replace fossil fuels. Also, because it contains around 44 percent protein, it can be used to make bioplastics. Cross notes that genetic engineers are modifying duckweeds to produce low-cost pharmaceuticals such as vaccines.