Northern Mexico is dominated by 2 deserts: the Desierto Sonorense (Sonoran Desert) west of the Sierra Madre Occidental, and the Desierto Chihuahuense (Chihuahuan Desert) occupying much of the Altiplan Central. The deserts are sparsely vegetated with cacti, agaves, yucca, scrub and short grasses.

West of Monclova in Coahuila state, the Cuatrociénegas valley is an oasis in the desert, renowned for its varied wildlife with dozens of endemic species including several each of turtle and fish. Between the Desierto Chihuahuense and the Sierra Madre Occidental and Oriental, as well as the Northeast of Mexico, a lot of land has been turned over to irrigation or grazing, or has become wasteland.

Most of world's 1000 cactus species are found in Mexico.