Low-Humidity-Tolerant Plants

Trees

• Low-humidity trees tend to have small or narrow leaves; less surface area allows less moisture to escape and doesn't capture as much sunlight. The mulga tree (Acacia aneura) tolerates drought, though it grows faster with regular irrigation. This Australian native reaches heights of 20 feet and blooms with puffy yellow flowers in spring. An evergreen, the mulga has silvery, linear foliage and grows well in reflected heat and full sun. Another evergreen, the palo blanco (A. willardiana) also tolerates drought; this 20-foot-tall Mexican native requires irrigation only once per month. It has an airy, open canopy and exfoliating bark. The olive tree (Olea europaea) also requires once-monthly irrigation. Native to Europe, the olive grows to 30 feet tall and produces white spring flowers, followed by edible fruits. It prefers sunny sites and tolerates reflected light.

Shrubs

• Many arid-region shrubs produce showy flowers that attract beneficial pollinating species. The Chihuahuan orchid shrub (Bauhinia lunarioides) thrives with once-monthly irrigation. Native to Texas and Mexico, this drought-tolerant shrub grows to 8 feet wide with a 6-foot spread. It produces pink-white, orchid-shaped blooms in spring and summer and has gray-green evergreen foliage. Also indigenous to the Southwest, the wooly butterfly bush (Buddleia marrubifolia) grows to 5 feet tall and has serrated, silvery-white foliage. This evergreen is named for the butterfly-attracting qualities of the spherical clusters of orange flowers it produces from spring through August. It thrives in full sun and requires only supplemental irrigation.

Perennials

• When planted in appropriate sites, perennials live for at least three years, and many survive for much longer. Paper flowers (Psilostrophe cooperi) grow in clumps up to 30 inches tall. These perennials produce long-lasting, delicate yellow flowers in spring. Native to the southwestern U.S., they have silver-green, hairy foliage, thrive in sunny sites and require only natural rainfall. As its name suggests, the Mexican sunflower (Tithonia fruticosa) is native to the southwestern deserts. This drought-tolerant perennial grows to 12 feet tall and produces 4-inch yellow flowers through the warmest months of the year. Mexican sunflowers thrive with biweekly watering and sunny exposures.

Ground Covers

• Drought-tolerant ground covers help prevent soil erosion from wind and the occasional rainstorm. The chocolate flower (Berlandiera lyrata) grows best when watered once per week. This perennial grows quickly and reaches heights of up to 2 feet. It produces fragrant yellow blossoms with brown centers from summer through fall and attracts pollinators. The common trumpet creeper (Campsis radicans), a vine that also grows prostrate as a ground cover, tolerates drought and requires only supplemental irrigation. This deciduous plant grows rapidly to 40 feet long and blooms with bright-orange flowers in summer. It grows best in full sun, though it tolerates partially shaded exposures.