Water Chestnuts

Trapa is a genus of floating annual aquatic plants in the Lythraceae family. A well-known species in the genus is Trapa natans, grown as a food crop in China and the Indian subcontinent.

Trapa was formerly placed in the separate family Trapaceae. However, molecular phylogenetic studies have recovered Trapa as the sister group of Sonneratia, with the clade comprising these two genera sister to a clade comprising Lagerstroemia and Duabanga. This four-genus clade is deeply nested within Lythraceae, and the APG system therefore includes Trapa in Lythraceae.