California's diverse geography ranges from the Pacific Coast in the west to the Sierra Nevada mountain range in the east; and from the redwood–Douglas fir forests in the northwest to the Mojave Desert in the southeast. The Central Valley, a major agricultural area, dominates the state's center. Though California is well-known for its warm Mediterranean climate, the large size of the state results in climates that vary from moist temperate rainforest in the north, to arid desert in the interior, as well as snowy alpine in the mountains.
Much of the state's lands were formed from sediment washed down the Mississippi River, leaving enormous deltas and vast areas of coastal marsh and swamp. These contain a rich southern biota; typical examples include birds such as ibis and egrets. There are also many species of tree frogs, and fish such as sturgeon and paddlefish. In more elevated areas, fire is a natural process in the landscape, and has produced extensive areas of longleaf pine forest and wet savannas. These support an exceptionally large number of plant species, including many species of orchids and carnivorous plants. Louisiana has more Native American tribes than any other southern state, including four that are federally recognized, ten that are state recognized, and four that have not yet received recognition.