By far the best plant choices, if you are looking for a low water and maintenance landscape, are those considered native to the area. Just keep in mind that not all Arizona native plants will survive in all parts of Arizona. For example, the Fremont cottonwood is native to riparian areas, but it is not a good choice as the water requirements are over 250 gallons per day for a mature tree. That’s not smart water use. Ponderosa Pines are right at home in Northern Arizona and in the mountains of Southern Arizona, but that doesn’t mean they will grow in Tucson.
Drought tolerant plants are those species that thrive on minimal irrigation. This does include native desert species, but not exclusively. For example, the Texas Ranger, even though not native to Arizona, is quite drought tolerant and happy in high heat and cold temperatures.
Desert adapted plants are those adapted to some desert conditions; but the caveat is not necessarily our desert. There are many deserts in the world, all of which contribute species to our list of choices, but many can’t take our freezing temperatures, blazing summer sun, or alkaline soils.
The best way to assure you are selecting plants that will not require excessive amounts of water or protection from frosts is to research what is hardy before buying. The Sunset Western Garden Book is worth purchasing, even if a used book, as it contains thousands of plants with detailed descriptions of the plant, where it is from, and where it will grow. In addition, unlike the USDA Hardiness Zone Map, which treats the United States not only as though it is flat, but ignores latitude, Sunset’s Climate Zone Maps are more realistic. Sunset’s Climate Zones take into account latitude, microclimates, valleys and mountains, which makes sense when you consider that the USDA lumps Tucson and Seattle into the same zone. Go figure.