The desert is an extreme landscape that boasts a surprising number of tree species that have adapted to the arid, hot conditions. The adaptations of desert trees have resulted in some of the most unusual-looking trees in the world. Many impressive desert specimens grow in abundance in the U.S., particularly throughout the Southwest.
America's desert trees exist throughout the Southwest in the Sonoran, Chihuahuan and Mojave deserts. The Mojave expands through California, southern Nevada, southwestern Utah and northwestern Arizona, while the Sonoran desert encompasses parts of Arizona, Mexico, California and Baja California. The Chihuahuan desert, meanwhile, goes through Texas and large areas of Mexico, New Mexico and southeastern Arizona.
Desert trees grow throughout the region, with some found primarily in desert basins, while others prefer the high elevations of rocky slopes. The flowering, fragrant desert willow (Chilopsis linearis) requires more water than most and can be found along desert washes and creeks. The Joshua tree (Yucca brevifolia) grows along slopes and mesas at elevations of up to 6,000 feet. A member of the bean family, the whitethorn acacia (Acacia constricta) is a small tree with a wide crown; it's found along floodplains and rocky mesas.
The size of desert tree varies, but Southwestern desert trees rarely grow to be enormous. The stout, aromatic elephant tree (Bursera microphylla) is a low-growing native of the Sonoran desert that reaches a maximum height of 10 feet. The pinyon pine (Pinus monophylla) of the Mojave desert grows to be between 20 to 40 feet. The flowering smoke tree (Dalea spinosa) of the Sonoran desert grows up to 20 feet tall.
Desert trees possess many features to help them cope with life in the desert. A native of the deserts of the West, including Mexico, the ponderosa pine (Pinus ponderosa) sports thick, tough bark that is almost completely fire-proof--a handy adaption in hot climates. The Rio Grande Cottonwood (Populus fremontii var. wislizenii) of the Southwest, also called the "water tree," has an extraordinarily deep root system that allows it to find water far beneath the surface. A new seedling may grow roots as deep as 5 feet.
Despite the often brutal living conditions of the desert, many desert trees are very long-lived. The desert fan palm (Washington filifera), which grows throughout the lowland deserts of California, can be up to 90 years old. It is not uncommon for the ponderosa pine to grow to be more than a century old. One 1,000-year-old ponderosa was once found in Colorado. The pinyon pine often lives 400 years, and may grow to be as old as 800 to 1,000 years.