Mild, moist air from the Pacific Ocean provides abundant rainfall to this biome. The forest is made up of a variety of conifers,ranging from giant redwoods along the coast of northern California to spruce, fir, and hemlock farther north. Moss often covers tree trunks and the forest floor. Flowering trees and shrubs such as dogwood and rhododendron are also abundant. Because of its lush vegetation, the northwestern coniferous forest is sometimes called "temperate rain forest."