The Mojave, Sonoran, and the Great Basin have created unique habitats for an unusual assemblage of plants. Some grow at seeps and springs, others emerge from cracks in the bedrock, and still others inhabit the sandbars within reach of the Colorado River's scouring currents. River and Desert Plants of the Grand Canyon, the first comprehensive field guide devoted to the plants that live below the canyon rims, describes more than 300 plant species, including ferns, grasses, forbs, shrubs, and trees.