The popular use of the word Campos (Pampas) - grassland - refers to an area covered by grasses and subshrubs with sparse (if any) trees of little importance in the landscape as a whole. To the botanist, Campos (Pampas) or grassland is more than a treeless tract of land: it is a type of low, xerophytic vegetation where water is scarse during a certain period. The plants have rigid leaves, which are rich in strenghening tissue. Campos is also used to refer to tracts of land covered solely with grasses or even partially aquatic.

The climate of typical grassland has a dry season and rainfall similar to that of the Cerrado (bushy savannah). In certain areas near the periphery, however, there is no dry season. In the south, for example, rain is evenly distributed throughout the year, and temperatures are lower. The flora of the grasslands is comprised of numerous species. Up to 34,600 seeds/square meters may be deposited upon the soil, which shows that the rupicolous flora is productive and very well adapted to the hardened, leached soils, which are scarcely permeable. A source of food is provided for small animals such as rodents, birds and many invertebrates.

The Campo inundável occurs in southern Brazil. In the state of Rio Grande do Sul, it goes by the name of marshy grassland. This type of grassland occurs inland as well as on the coast. These areas actually marshes; they are permanently wet and are densely covered with grasses, sedges, and several aquatic macrophytes. Other species which grow there include the horse tail (fern-like plant: Equisetum), popularly known as cavalinha. There are also many Xyridaceae (family of acaulescent marsh plants) and Eriocaulaceae (family of herbaceous plants with spherical, white inflorescenses).

There is evidence that several animals, especially mammals and birds of neighboring ecosystems, frequently visit the grassland. The present inane, tendency to exterminate wildlife has so decimated populations of important species that, nowadays, they are a rare sight indeed. The state of Rio Grande do Sul and Santa Catarina, there are Campos inundáveis which are genuine reserves for fauna. In the ecosystem, a considerable number of individuals of the aquatic Anatidae (family of birds which includes swans, geese and ducks) and marsh birds are found.