alisma

Alisma, commonly known as water plantain, is a genus of herbaceous aquatic plants belonging to the family Alismataceae. These plants are found in shallow water bodies, marshes, and wet areas across temperate and tropical regions worldwide. Alisma species are characterized by their basal rosette of leaves and erect flower stalks bearing small, typically white or pink flowers. The leaves are often lance-shaped or ovate and can be either submerged or emersed depending on the water level. The flowers, which usually appear in summer, have three petals and three sepals, and are followed by small, achenes that are aggregated into a head.

The genus Alisma contains several species, with Alisma plantago-aquatica being one of the most widespread. These plants play a role in aquatic ecosystems by providing habitat and food for various invertebrates and fish. Some species have historical uses in traditional medicine, though scientific validation for these uses is often limited. The propagation of Alisma typically occurs through seeds, which can remain viable in the sediment for extended periods, or through rhizomes. While generally considered a beneficial component of wetlands, dense stands of Alisma can occasionally be problematic in managed waterways or irrigation systems, requiring control measures.