Hydrocharitaceae

Hydrocharitaceae is a family of aquatic flowering plants in the order Alismatales. Members inhabit freshwater and brackish environments worldwide, from temperate to tropical regions. They are adapted to life submerged or at the water surface, often with rhizomes or tubers for storage and propagation. All members are monocots, and their flowers are typically small and sometimes sessile, produced on emergent or floating structures.

Morphology and ecology vary among genera, but most species are herbaceous aquatic or amphibious plants. Leaves can be linear and submerged, broad and floating, or a combination of both. Roots are often reduced to a rhizome system, with nutrient uptake occurring through leaves and stems as well. Reproduction occurs sexually via small flowers and seeds, and vegetatively through fragmentation, runners, or tubers, facilitating rapid spread in suitable watery habitats.

Genera commonly cited within Hydrocharitaceae include Hydrilla, Elodea, Egeria, Vallisneria, Najas, Limnobium, Hydrocharis, and Stratiotes. The family’s taxonomy has been reshaped by molecular studies, leading to changes in the circumscription of some genera and their placement within Hydrocharitaceae in various classifications. Despite this fluidity, the family is consistently recognized for its freshwater aquatic members.

Ecology and human relevance: hydrocharitaceous plants are important components of aquatic ecosystems, providing habitat and food for invertebrates and fish. They are popular in aquaria and water gardens for their rapid growth and visual appeal. However, several species, notably Hydrilla verticillata, can become invasive, forming dense mats that disrupt water flow, outcompete native vegetation, and complicate management of infested waters.