Mesquites bring character to a landscape, are tolerant of heat

  Desert plants have adapted to the extremes of heat aridity by using both physical and behavioral mechanisms. Plants that have adapted by altering their physical structure are called xerophytes. These are plants that have adapted to low water availability.

  Xerophytes, such as cacti, usually have special means of storing and conserving water. They often have few or no leaves, which reduce transpiration. Xerophyte plants that have altered their physical structure to survive extreme heat and lack of water are the largest group of such plants living in the deserts of the Southwest. If you have ever heard the term xeriscape landscaping, this is in reference to having only plants that fit this category in rocky, sandy soils. This means primarily cacti, which require none to very little maintenance and watering.

  Cacti store water in the core of both roots and stems, enabling them to survive years of drought on water collected in a single rainfall.

  Phreatophytes are plants that have adapted to environments by growing extremely long roots, allowing them to acquire moisture at or near the water table. The mesquite tree has adapted to desert conditions by developing such long roots. In fact, the mesquites are considered to have the longest root of any desert plant and have been recorded to penetrate depths of 150 feet to search out water.

  Mesquites are abundant throughout all the Southwestern deserts. If you are looking for a bold desert tree with great character, and want to have a true feeling of the West, a good choice is one of the varieties of the mesquite tree. They are very adaptable and tolerant of adverse conditions and exposure.

  Mesquite trees usually have dark, sometimes rough bark, with a spreading crown composed of numerous, finely cut leaflets. In youth they are often thorny, but the thorns tend to disappear with age as growth slows. In the spring, yellowish catkins flowers appear, followed by yellowish seed pods which may be straight, twisted, or curved, depending on the species.

  Mesquites are not true desert plants in the same sense as cacti. They can live on little water, but adverse conditions keep them small and cause twisted forms. With regular irrigation, the mesquite will gain size and keeps its picturesque form. Ample irrigation will produce a large tree faster.

  All mesquites twisted or not, have outstanding character and blend with a garden or natural landscape equally well. They are most attractive when trained as multiple-trunk trees. Once a mesquite has obtained a desired size, its growth will be slowed by reducing irrigation. A mesquite tree is one of the most effective plants for summer shade and sinter sun.

  Since the roots can be quite invasive do not plant near septic tanks or leaching fields. Plant from containers anytime, spacing 20 feet or more apart for a fast canopy. Be sure to stake young trees for support.

  Because mesquite trees have hybridized and look different in varying environments, knowing the botanical name will help you choose the tree that is right for a particular landscape use. Here is a list of mesquite trees and their botanical names to help you decide which tree is best for your landscape:

  Argentine mesquite (Prosopis alba): This is perhaps the fastest growing mesquite and is quite vigorous. Rough/dark trunks tend to grow more vertical than other mesquite trees, and a good percentage have the narrow vase shape required for parking lots and narrow planting spaces. The crown is spreading, blue-green in color and dense. With irrigation it can become a substantial tree in 5 or 6 years. You will usually find it labeled  P alba.

  Chilean mesquite (Prosopis chilensis): This is a rapid growing tree and is more upright in appearance, and is thornless. Trunks are twisted with dark, coarse textured bark. Because of its rapid growth it needs ample room for proper development. The foliage of the Chilean mesquite is more open and ferny and the tree is more evergreen. It bears fewer blooms and the few seed pods are curved and hang in clusters. This one you will find labeled P. chilensis.

  South American hybrid (Prosopis hybrid), is the second most common name for locating this tree in most nurseries. Trees offered in nurseries under the name P. chilensis are collected locally, and believed to be native to the Yuma-Imperial Valley region of California into Mexico. The hybrid is vigorous in appearance with a wide spreading crown and deep green leaflets.

  It is deciduous and has more blossoms and seeds than the true Chilean mesquite and looks more rugged in a desert setting.

  Velvet mesquite/Arizona mesquite (Prosopis velutina), is usually labeled as P. juliflora velutina. The foliage of the velvet mesquite is soft and gray green with a velvety appearance from a distance. Leaflets are fuzzy and small attached to nubby twigs which are usually thornless. This is the mesquite surrounding populated areas of Arizona. It is the main source for firewood, woodworking, and cabinet making. This tree is harder to find in nurseries than others, which is a shame because it blends the best with the desert. It is deciduous and loses it leaves with the first cold spell.

  Honey mesquite/Texas mesquite (Prosopis glandulosa): This tree is usually associated with Texas, and is quite different from other mesquite. While the other mesquite trees are part of the Leguminosae (fabaceae) family the Honey mesquite is part of the Mimosaceae, Mimosa family. It is a medium to small tree with a rounded crown and crooked, drooping branches. The feathery foliage is a brighter green with straight paired spines on twigs.

  The Honey mesquite reaches an average height of 20-30 feet but can reach as high as 50 feet. It is not as widely used in the West as most other mesquites listed.

  Plant mesquite trees in full sun, or reflected heat. All mesquites produce messy seed pods and have leaf drop. In the late spring, early summer they show off an abundance of blooms that are near white to pale yellow in color.

  After planting your mesquite tree, water it thoroughly and continue to water every three or four days for the first two to three weeks. Thereafter, water every seven to 10 days for the first year.

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Debi Papp is a member of the Yuma Garden Club and other gardening organizations. She may be reached at 928-783-3189 or greenthumbs1@roadrunner.com.