The vegetation of the American continents varies greatly between different regions. This is the result of two factors: 

1. The Americas encompass a large surface area from the shores of the Arctic Ocean in the north and nearing the continent of Antarctica in the south.
2. The Americas have regions of varied elevation. These include lowlands, highlands and mountain ranges. The mountain range of the American Cordilleras (which is comprised of the North American Rockies and the South American Andes) has an especially significant effect on the climatic conditions found on the two continents. 

From north to south, the American vegetation zones are:

1. Tundra (grasses, mosses, lichens).
2. Coniferous forest.
3. Temperate grassland and broadleaf forest.
4. Rainforest.

In addition, mountain ranges are characterized by mountain vegetation (coniferous forest and alpine tundra). Mediterranean vegetation or chaparral is found in California in Western North America as well as in Chile in Western South America.