No trees grow on the Antarctic continent.
The Pampas
llanos would be it
I am pretty sure this is called a tundra.
The flat treeless plains of Argentina are known as the Pampas. These vast grasslands cover a large portion of central Argentina and are a significant region for agriculture, particularly for livestock grazing and crop cultivation. The Pampas are also home to a variety of wildlife, including species like the guanaco and the rheas.
It is found on every continent expect Antarctica. Because Antarctica is the coldest continent. Insects can die in Antarctica.
Using this description of 'plains': "An extensive, level, usually treeless area of land," one could consider vast expanses of Antarctica as 'plains'. However, since the continent is covered -- 98% -- by ice, and since it's too cold there for life to survive, there is no food chain there, so no trees can grow: Antarctica is often described as having 'long horizons', based on the flatness of the ice that covers the continent. This is especially true at the South Pole.
The name given to an area that is a flat treeless plain is a steppe.
Treeless Pain
Antarctica
Another name for a treeless plain is a steppe or a prairie. These landscapes are characterized by a lack of trees and are often covered in grasses or shrubs.
An exsensive plain, esp. one without trees.
Antarctica's real name is Antarctica.