Lemna aequinoctialis, commonly known as Lesser Duckweed, is a deciduous perennial herb that thrives in still or slow-moving freshwater habitats such as ponds, marshes, and quiet streams in tropical and subtropical regions. It is native to a wide range including Tropical Africa, South America, and South and Southeast Asia. Lesser Duckweed is characterized by its small, free-floating fronds that are typically 3-nerved and green, measuring up to 6 mm in length. Although it rarely flowers, when it does, the flowers are inconspicuous with a single ovule and a small utricular scale that is open on one side. The seeds are distinctive with 8–26 ribs.

This plant is valued for its rapid growth and ability to cover water surfaces, which can help reduce algae growth by limiting light penetration. It is used in water gardens and as a biological filter in aquaculture and wastewater treatment systems. Lesser Duckweed prefers full sun but can tolerate partial shade. It requires an aquatic environment and can grow in water with varying nutrient levels, although it thrives in nutrient-rich conditions. While it is low maintenance, it can become invasive in some settings, outcompeting native aquatic plants.CC BY-SA 4.0