First record in the Mexican flora of Hygrophila polysperma (Acanthaceae), an aquatic weed

Abstract

The presence in Mexico of the aquatic weed Hygrophila polysperma is reported for the first time. Data regarding history in America, morphology, and distribution in Tamaulipas are provided. A key is included to distinguish this species from the Mexican native, H. costata. Finally, the threat that this introduced plant represents for artificial and natural aquatic ecosystems in Mexico is discussed.