Within the framework of phytosociological investigations on the aquatic ecosystems of northern Iran, Ammannia coccinea is reported for the first time here from the Flora Iranica area. It was collected in wet and muddy habitats of submontane water bodies and in rice fields along the Haraz road, on the way to Amol, Iran. An identification key is provided for the five species already reported from Iran. Migratory birds are considered the main agents of distribution, as noted for other plant species in northern and northwestern Iran.
