XVI International Botanical Congess

Uruguay with a surface of 178,000 km2 owns a great diversity of wetlands characteristic of temperate climate. The more characteristic wetland are freshwater marshes, permanently or seasonally inundated, in flat areas or in floodplains. In this work the vascular aquatic plants were relevated and 232 species were found, corresponding to 49 families of angiosperms and ferns (20 families, 50 genus, 135 species of monocotyledons, 23/40/86 dicotyledons,6/8/11 ferns). The most represented species belong to the Cyperaceae and Poaceae. In relation to the geographical origin, 34% of the species are native of the Americas, 8% are native of South America, 37% are native of the south of South America (north of Argentina, south of Brazil, south of Paraguay, Uruguay), 6% are cosmopolitan, 6% others and 9% are endemic of Uruguay or of very restricted areas around Uruguay. Family keys, geographic distribution maps and resumed table are presented.