Wolffia globosa or Water-meal can weigh about 1/190,000 of an ounce, equivalent to two grains of table salt. They are very hard to see! if you tried to fill a thimble with them, it is estimated that you would need some 5000 plants!
Wolffia is a genus of 9 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. The plant itself averages 1/42″ long and 1/85″ wide or about the size of one candy sprinkle. The plant is found in quiet freshwater lakes or marshes with species worldwide. 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 percent protein, 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.
Each Wolffia flower consists of a single pistil and stamen; it also produces the world’s smallest fruit, called a utricle.