Desert Trees & Cacti

Desert Conditions

• Desert covers nearly one-third of the Earth's surface, and is classified as an area with little rainfall that features extreme temperatures, both hot and cold. These areas receive less than 10 inches of rain per year, not enough to sustain most types of plants. There are a number of different desert types, and they range from open and sandy to an area filled with large rocks and gravel. In order to thrive, a number of specialty desert-dwelling plants have adapted water conservation methods and ways to protect themselves against sun, heat and other difficult conditions.

Cacti

• Members of the cacti family are widely used in desert landscapes, and are particularly popular is areas that suffer regular drought conditions. These plants rage greatly in size, from 3 inches in height to as tall as 30 to 40 feet. These desert favorites have adapted to survive on the limited water available in arid regions. Aside from having spines instead of leaves and succulent stems, they have roots that sit close to the soil's surface, which permits greater water absorption. The characteristic pleating on the surface of cacti serves to channel water toward the roots. Spines are leaf equivalents but require significantly less water. They provide shade to the stem and keep the plant cool. The prickly pear (Opuntia phaeacantha), barrel cactus (Ferocactus cylindraceus) and the organ pipe cactus (Lemaireocereus Thurberi) are among the most widely used in landscaping.

Succulents

• There are more than 60 families and 300 different species of succulent plants. As with cacti, these plants have structural adaptations that make them ideal for desert settings. Succulents have a unique water-storing tissue that makes up their leaves, stems or roots, and often a combination of the three. This tissue makes it possible for these plants to hold onto the limited water available. Leaf succulents, including aloe and the zebra plant (Haworthia attenuate), have leaves that are composed of these specialized cells. Stem succulents, which encompass almost all cacti varieties, generally have no leaves, which aids in reducing evaporation. Root succulents store water in their roots, away from the sun. Leaves may be nonexistent, but are more often shed during extended dry periods. The Mexican boulder (Calibanus hookeri) and the gearstem cactus (Peniocereus striatus) are both members.

Trees

• As with other desert-friendly plants, certain trees have adapted to thrive in arid zones. The bark of these trees tends to be thick and dense, which improves water retention. The root systems of desert trees are shallow, and rarely grow lower than a few inches below the ground. These trees tend to be slow-growing, but may reach mature heights of 30 feet. A limited number of small leaves provide shade to the plant without requiring too much water. Among the most common of these are the mesquite (Prosopis juliflora), Palo verde (cercidium microphyllum) and the Mexican elder (Sambacus Mexicana).