Geography of South America world by drainage area—the Amazon River and the more southerly Paraná River. The other major river of this central lowland is the Orinoco River, which has a natural channel linking it with the Amazon. Most of this central lowland is sparsely populated because the soils are heavily leached, but in the south is the very fertile pampas of Argentina—one of the world's major food-producing regions where wheat and beef cattle are pre-eminent. The natural vegetation of the northern lowlands are either savanna in the northern "llanos" and southern "campos", or tropical rainforest throughout most of the Amazon basin. Efforts to
Mesopotamia, Argentina only a thin fertile layer that can easily be washed away. Corrientes is marshy and wooded, with low hills. Entre Ríos is covered with fertile pasture land stretching into Uruguay. The flora of Mesopotamia includes the yatay palm ("Syagrus yatay", "Butia yatay"), which is a protected species in the El Palmar National Park, and the "Araucaria angustifolia" (Paraná pine tree). Tree ferns, orchids and large trees can also be found. "Yerba mate" ("Ilex paraguariensis") is grown largely in Mesopotamia; 1,800 square kilometres of Misiones are devoted to its production. The region is also important for cattle and sheep, poultry, linseed,