The plants adapted to the desert biome have had to adjust to extremes in temperature and in water availability. Botanists who study desert plants have different classifications for the species that grow there, categorizing plants according to their physical features in many cases. In addition to a variety of cactus types, other plants that grow in American deserts include wildflowers, shrubs and trees.

Cacti

The many kinds of cacti in the American deserts are xerophytes, meaning they have adapted to the desert with physical alterations, according to the Desert USA website. Cacti can store water and they lack leaves, which reduces the loss of water to the air. The outer surface of cacti is like a waterproof skin, which keeps moisture inside the plant. A huge assortment of cacti thrive in the adverse conditions of the desert, with such familiar species as the barrel cactus, the saguaro cactus, the prickly pear cactus and the organ pipe cactus all found there in abundance. Other less familiar kinds of cacti are the desert Christmas cactus, the fishhook cactus, the cholla cactus, the beavertail cactus and the chain fruit cactus.

Trees and Shrubs

Trees such as the California fan palm, cottonwood, smoke tree, mesquite tree, Palo Verde tree, elephant tree and ponderosa pine grow in various parts of the desert biome. Shrubs such as whitethorn acacia, cocklebur, juniper and creosote bush also can withstand the desert environment. An odd plant called ocotillo looks like a cross between a shrub and a type of grass; it grows out from a central base and possesses spiny woody stems that wait until after a rain to produce leaves. The ocotillo has handsome red flowers in the late spring; the amount of rainfall affects how long they bloom.

Wildflowers

Wildflowers that seem to appear suddenly after a rain are a trait of the Southwest desert biome. These flowers are annuals, but a more accurate description for them is "ephemeral," as they have a much-accelerated life cycle that takes advantage of the existing conditions during and short after rain falls in the desert. Wildflower species such as Apache plume, ghost flower, filaree storkbill, popcorn flower and prickly poppies gained their names from some aspect of the plant. The ghost flower, for example, is translucent, giving someone the impression that it is a fleeting specter. Other desert wildflowers include desert five-spot, desert mariposa lily, desert pincushion, desert paintbrush, cave primrose and woolly daisy.