Diversity and distribution of the aquatic vascular flora of Tamaulipas, Mexico

Abstract

The aquatic environments (wetlands) are among the more threatened ecosystems, with their biodiversity poorly known. As a first step toward a better knowledge of the aquatic vascular plant diversity of northeastern Mexico, in this paper the diversity and distribution of the aquatic plants (hydrophytes) recorded and documented in the state of Tamaulipas are discussed. It is one of the three states comprising the northeastern of Mexico and includes the largest area of wetlands. The species are classified by type, biological form and life form. A number of 426 species, belonging to 213 genera and 85 families are recorded; such a figure represents 57% of the total vascular plants species recorded in all Mexico. True aquatics represented 22.8% of the species, as marginal aquatics 43.7%, and wetland tolerants 33.5%. By habit, 88.5% of the species are herbs, 6.1% shrubs and 5.4% trees; on the other hand, the dominant life form was emergent rooted hydrophytes (376 species, 88.3%). A high percentage of species are widespread, distributed either all along America or reaching part of the Old World; only nine species were recorded as endemic to Mexico (one endemic to Tamaulipas). The state of Tamaulipas is an important reservoir of species associated with wetlands and constitutes a relevant biogeographic area, due to the fact that in its territory the geographic limit of a number of boreal and meridional elements is found.