Palo verde trees (Pakinsonia spp.) are deciduous, medium-sized trees and large shrubs from the Fabaceae or bean family. The drought tolerance of palo verdes makes them plants of choice in xeriscape or water conservative landscapes. All palo verdes except P. praecox are natives of the Sonoran desert, the natural range of P. praecox extending into South America. Numerous adaptations of palo verdes increase their tolerance for their harsh native environmental conditions.
The green-colored bark of the palo verde tree is among its most important adaptations. Though the trees are deciduous, the loss of leaves does not affect the process of photosynthesis or the use of sunlight to produce energy and food. Palo verde trees are able to continue photosynthesis with their green-colored bark. The tree not only loses leaves but also some of its branches and stems during periods of extreme drought.
The palo verde trees bloom with small yellow flowers that grow along the edges of tree branches. The flowers are especially adapted to form pods full of seeds that attract a number of animals. As the animals eliminate the seeds from their bodies after digestion and spread them throughout the desert, it helps the palo verde tree spread far and wide. The seeds grow easily into new trees, making these flowers an important reproductive adaptation of the palo verde.
Palo verdes are among the plants that are referred to as drought deciduous. Being drought deciduous is among the important adaptations of many desert plants. These plants lose their foliage under dry and hot weather condition with the aim to help conserve the water that may be lost otherwise through transpiration. Palo verdes have 1-inch-long, compound, pinnate, round leaflets.
The roots of the palo verde are especially adapted to seek out water sources from deep within the ground to help trees survive in their arid native environment. Though the palo verdes are only medium-sized trees or large shrubs growing to about 25 feet or less, the roots extend as far as 100 feet into the ground, cites Bruce Grubs in “A Falcon Guide to Saguaro National Park and the Santa Catalina Mountains.”