Nearly worldwide in temperate and tropical regions.
Genera 2, species ca. 50 (2 genera, 11 species in the flora).
The affinities of Elatinaceae have long been uncertain; relationships with Caryophyllaceae and Clusiaceae have been proposed (G. C. Tucker 1986). Recent molecular work, combined with a review of morphology, indicates a sister relationship with Malpighiaceae (C. C. Davis and M. W. Chase 2004; K. Wurdack and Davis 2009).
|1||Sepals 5, carinate; petals 5; inflorescences usually cymes, rarely solitary flowers, pedicels present; plants glandular-pubescent; stems solid or pithy.||Bergia|
|1||Sepals 2–4, not carinate; petals (0 or) 2–4; inflorescences solitary flowers, pedicels present or absent, or if flowers 2 per node (E. chilensis) then pedicels absent; plants glabrous; stems with longitudinal air spaces.||Elatine|