Lemna minor

Lemna minor (Common Duckweed or Lesser Duckweed) is a species of Lemna (duckweed) with a subcosmopolitan distribution, native throughout most of Africa, Asia, Europe and North America, occurring everywhere that freshwater ponds and slow-moving streams occur, except for arctic and subarctic climates. It is not reported as native in Australasia or South America, though is naturalised there. It is a floating freshwater aquatic plant, with one, two or three leaves each with a single root hanging in the water; as more leaves grow, the plants divide and become separate individuals. The root is 1-2 centimeter long. The leaves are oval, 1-8 millimeter long and 0.6-5 millimeter broad, light green, with three (rarely five) veins, and small air spaces to assist flotation. It propagates mainly by division, and flowers are rarely produced; when produced, they are about 1 millimeter diameter, with a cup-shaped membranous scale containing a single ovule and two stamens. The seed is 1 millimeter long, ribbed with 8-15 ribs.