Comb-Leaved Mermaidweed

<em>Proserpinaca pectinata</em>, the comb-leaved mermaidweed, is a semi-aquatic flowering plant in the family Haloragaceae, assessed as Least Concern on the IUCN Red List. It occurs in the freshwater wetlands of Canada and Cuba, growing in shallow water, pond margins, bogs, and wet meadows. The species is notable for its heterophylly, producing distinctly different leaf forms above and below the waterline: emergent leaves are linear or toothed while submerged leaves are deeply pinnately divided, resembling a comb — the feature that gives the plant its common name. This leaf-form plasticity is an adaptation to variable water levels in its riparian and wetland habitat. <em>P. pectinata</em> is a rooted aquatic plant that grows in nutrient-poor to moderately fertile waters and is sometimes cultivated in freshwater aquaria for its ornamental submerged foliage. No quantitative biological metrics are available for this species.