Elatine, commonly known as waterworts, is a genus of about 25 species of small aquatic plants and the principal genus in the family Elatinaceae (order Malpighiales). The family contains only one other genus, making Elatine the dominant member of this small lineage within the flowering plants.
Waterworts are annual or perennial herbs that grow in wet habitats — shallow freshwater margins, mudflats, temporary pools, and the edges of lakes and streams. They are cosmopolitan in distribution, with species recorded across Europe, Asia, North America, South America, and Australasia. The genus includes both fully submerged aquatic forms and amphibious plants that can grow on wet mud when water levels recede.
Individual plants are typically small and inconspicuous, with slender, often creeping or mat-forming stems. Leaves are opposite and simple, and flowers are minute, usually with two to four petals, borne singly in the leaf axils. Despite their diminutive size, waterworts can form dense mats in suitable conditions and are ecologically important as pioneers on exposed wet substrates.
Notable species in the genus include Elatine hexandra, Elatine triandra, Elatine brachysperma, Elatine rubella, and Elatine gussonei, the last of which is a rare Mediterranean endemic of conservation concern.
Distribution
Waterworts (Elatine) are distributed worldwide, growing in shallow freshwater habitats — lake margins, slow streams, temporary pools, and exposed mudflats — across Europe, Asia, the Americas, and Australasia.
Ecology
Species of Elatine are aquatic or amphibious herbs adapted to wet, often seasonally fluctuating environments. They colonise exposed mud and shallow water, functioning as early-successional pioneers on disturbed wet substrates. Both annual and perennial life strategies are represented in the genus.
Taxonomy Notes
Elatine is one of only two genera in the family Elatinaceae, which belongs to the large and diverse order Malpighiales within the eudicots. The genus contains approximately 25 accepted species, though delimitation of some taxa has historically been uncertain due to the plants' small size and morphological plasticity.
