Which desert has the greatest variety of plants in North America?

The Sonoran Desert is recognized as having the most diverse vegetation of all the deserts in North America.1

While the Chihuahuan Desert is also noted for its significant biological diversity—supporting more than 3,500 plant species, including nearly one-fourth of the world's cacti—the Sonoran Desert is explicitly identified as possessing the greatest variety of plant life among the North American desert regions. Its subtropical climate and unique environmental conditions support a wide array of signature species, including the saguaro, barrel cactus, organ-pipe cactus, prickly pear, ocotillo, and various trees such as ironwood and palo verde.123