) is a flowering aquatic plant in the family Araceae, native to Europe, Africa, and parts of Asia. It is also known as Spotless watermeal. Rootless watermeal is the smallest vascular plant on Earth.
Rootless watermeal is a rootless plant grows in calm water bodies. It rarely exceeds 1 mm in length and always float on the surface of the water. The green part of the plant or frond, is a sphere measuring 1mm wide, with a flat top that floats at the water's surface. Rootless watermeal has a few rows of stomata. It produces a minute flower completes with a stamen and a pistil.
Rootless watermeal can produce its own energy via photosynthesis, or absorb it from the dissolved carbon in the environment. During cooler condition, the plant becomes dormant and overwinter as a turion and sinks to the bed of the water. Each turion contains about 40% starch.
The green part of the rootless watermeal contains about 40% proteins by dry weight, amino acids, dietary minerals and trace elements. It has been used as a cheap food source in Thailand, Myanmar and Laos, where it is known as Khai-nam or eggs of the water.
Rootless watermeal is also useful in agricultural and municipal water treatment, in absorbing and metabolize pollutant. It grows quickly and can take up a large amount of nitrogen and phosphorus from the water.
Propagation is by vegetative reproduction.
Rootless Watermeal (Wolffia arrhiza)