Which plant is known as the smallest of flowering plants?

Watermeal is known as the smallest of flowering plants. It belongs to the family Lemnaceae and is characterized by its tiny, free-floating structure that typically measures less than 1 millimeter in diameter. Despite its small size, it produces flowers, which is a distinguishing feature of flowering plants. Watermeal plays a significant role in aquatic ecosystems, providing food for various aquatic organisms and helping in nutrient cycling.

In contrast, the other options are larger and do not hold the title of the smallest flowering plant. Common Duckweed and Giant Duckweed are also members of the Lemnaceae family but are considerably larger than watermeal. Eurasian Watermilfoil, while a significant aquatic plant, is also larger and often considered an invasive species in many areas. Therefore, watermeal stands out due to its unique size and the fact that it is indeed a flowering plant.