First record of the aquatic weed Alternanthera philoxeroides (Amaranthaceae) for Mexico

Abstract

Alternanthera philoxeroides (Mart.) Griseb. is an alien weed in some parts of the world and is often a serious invader of aquatic habitats. Here, it is reported for the first time in Mexico. The botanical material was collected on the banks of Rio Bravo, in the municipality of Matamoros, Tamaulipas. A detailed morphological description and an illustration of this species are included, in addition to a key to the species of Alternanthera occurring in Tamaulipas. The plant is relevant to the conservation of the native flora of Mexico; so, we recommend eradication of the populations described and take actions to prevent its spread to other wetlands in the country.