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The Pros and Cons of Mesquite Trees

Titan mesquite tree headerMesquite trees are just as much a part of our desert environment as the iconic saguaro cactus, quail, coyotes, or any other symbol of life in the southwest. However, they certainly don’t get as much attention.

Mesquite trees can either go unnoticed as a background tree not worthy of attention, or they can be a hotly contested topic – with points showing the benefits of mesquite trees, but also equal arguments against them.

In this article, we will:

  • introduce you to the mesquite trees most commonly found in the Phoenix and Anthem areas,
  • share the benefits of adding a mesquite tree to your landscape, and
  • go over some of the negative aspects of mesquite trees you may want to consider before planting.

No matter your thoughts on whether a mesquite tree would work well for your property, they are a vital part of the desert ecosystem and an important tree in the desert southwest.

Types of Mesquite Trees in Arizona

While there are over 40 species of mesquite trees found worldwide, there are three types that usually grow in Arizona, and specifically the Phoenix and Anthem areas:

  • Velvet mesquite, also known as native mesquite or Arizona mesquite
  • Honey mesquite, also known as Texas mesquite
  • Screwbean mesquite, also known as the tornillo mesquite

In areas where varieties of mesquite trees overlap, there are some natural hybrids.

Chilean and Argentinian mesquites are sometimes introduced in Southern Arizona, but they tend not to do well in our winters. Still, you might see some black mesquites (Prosopsis nigra), Argentine mesquites (Prosopsis alba), and Chilean mesquites (Prosopsis chilensis) growing or sold at nurseries. The Chilean mesquite, in particular, is popular because of its smaller thorns and filtered shade.

Are mesquites a tree or a shrub?

You may be surprised to learn that mesquite is the most common tree/shrub in the desert southwest. In shallow soil, mesquites may grow to only 3 feet tall, making them a shrub. But if the soil is deep and there is enough irrigation, mesquite trees can grow 30 to 50 feet tall.

Next, we’ll go over the three most common types of mesquite trees in more detail.

Velvet Mesquite (Prosopis velutina)

Titan Velvet MesquiteHeight: 30-50 feet

Spread: 30-50 feet

Growth rate: Slow to moderate (moderate to rapid with abundant water)

Where it grows: Southern Arizona

Bark: Dark brown, rough, shaggy

Shade: Casts light, filtered shade, making it an ideal nurse tree

Leaves: Gray-green with 12-30 small leaflets on one or two pairs of pinnae

Flowers: Cream-colored or pale yellow, 2-3 inches long

Thorns: Small thorns (up to one inch long), becoming less thorny as the tree matures because the yellow spines typically only grown on young branches

Velvet mesquites are so named because of the tiny hairs that cover young trees. They are the most common type of mesquite tree found throughout southern Arizona. Often multi-trunked, they are found growing in dry grasslands or near streams.

The wood from velvet mesquites is used for furniture and can be popular because of its unique grain. If well cared-for, velvet mesquites can live for several hundred years.

Honey Mesquite (Prosopis glandulosa)

Titan Honey MesquiteHeight: 15-40 feet

Spread: 15-40 feet

Growth rate: Medium to fast growing, especially when watered

Where it grows: Southwestern U.S. and northern Mexico

Bark: Tan and smooth when young, becoming more rough and dark over time

Shade: Creates dappled shade

Leaves: 6-24 leaflets on 1-2 pairs of pinnae

Flowers: White or pale yellow in spring and summer

Thorns: Reddish thorns, although some thornless cultivars are available

Honey mesquites are recognized by their longer, drooping branches, often growing in a weeping form. In their natural habitat, the trunk often grows crooked. The tree itself grows into a rounded canopy of fern-like leaves. The honey mesquite tree gets its name because it is a popular pollen source for bees and other pollinators.

Screwbean Mesquite (Prosopis pubescens)

Titan screwbean mesquite
Screwbean mesquite image courtesy of 
pompilid - Own work, CC BY-SA 3.0 

Height: 25 feet

Spread: 25 feet

Growth rate: Very slowly without irrigation

Where it grows: Sonoran desert, Chihuahuan desert, Arizona, Texas, New Mexico

Bark: Shaggy and flaky on older trees, can sometimes peel

Shade: Filtered

Leaves: Smaller than other mesquites, one pair of pinnae with 5-9 pairs of leaflets

Flowers: Bright yellow or white, 3 inch-long, conical blossoms

Thorns: ¾ to 1 inch-long white thorns appear in pairs on branches

The screwbean mesquite is named after the seedpods, which can look like a spring or screw. The alternate name, “Tornillo,” means screw in Spanish. It often has multiple stems and has a spreading crown that is shaped like a vase.

See photos of several kinds of mesquite trees at this link.

The Positives and Negatives of Mesquite Trees

While mesquite trees (or shrubs) are an important part of our desert landscape, they do not work in every landscape. In fact, there are positives and negatives to almost every aspect of mesquites.

Roots

Mesquites have two kinds of roots:

  • lateral roots (which most trees have) that are incredibly long, often extending far beyond the tree’s canopy, and
  • a tap root, which can grow deep into the soil, sometimes as far as 150 to 200 feet!

Thanks to this combination root system, mesquites are extremely drought tolerant. (Note: in our current exceptional drought status, even drought tolerant trees can benefit from a long and deep watering).

A mesquite tree’s far-reaching roots can also be a cause for concern. It can be difficult or nearly impossible to grow anything else under a mesquite tree (or within several feet of it) as the mesquite tends to soak up all the available moisture. While no tree roots can break into pipes, they will find their way in if there is even a tiny crack, leading to costly repairs.

 

Thorns

Mesquite trees have thorns that grow up to 3 inches long. These thorns can be painful to step on and a nuisance if the branches are near a walkway. Some people have an allergic reaction to the thorns of mesquite trees, so use gardening gloves if you are handling any mesquite branches.

These thorns can work to your advantage, however, if you need some sort of protective screen. When mesquite trees are grown as short shrubs, several of them grown close together can provide not only privacy but a nearly impenetrable security barrier.

If you like mesquites but the thorns are the only thing deterring you from getting one, there are some thornless hybrids available.

Nitrogen

Mesquites are part of the legume family (think peas and peanuts), and as such are unique in that they work with specific kinds of bacteria to add nitrogen to the soil. What this means is that they essentially fertilize themselves and any neighboring plants.

Nitrogen-rich soil is not always wanted or needed, however, so knowing the composition of your property’s soil and what it needs is an important first step before planting anything.

Seed Pods

Mesquite seed pods have been a food source for animals and humans for a long time. Unlike most other local trees, though, mesquite seed pods are used even now. You can collect your own seed pods by picking them off the tree and have them ground into a flour that is slightly sweet and used in a variety of baking products (and some local coffees!). Mesquite flour is beneficial for people with diabetes, as it can help control blood sugar levels.

Check out this guide from Desert Harvesters for harvesting, storing, and processing mesquite pods. You’ll also find an informative set of FAQs about mesquite tree pods on the Desert harvesters website.

Seed pods were a popular food choice for livestock, especially when other feed such as grass was unavailable. During the Civil War, they were roasted or boiled to create something similar to coffee.

Mesquite trees produce an abundance of seed pods, so be prepared for the “litter” of seeds every year. The seeds have been shown to be viable for up to 50 years, which is one of the reasons that mesquite trees are able to survive in many areas.

Depending on the weather conditions each year, a mesquite tree may produce fewer seed pods due to frost damage to the flowers, drought, or other environmental factors.

There are some hybrids that are “seedless” if you want to avoid the mess from the seed pods, but keep in mind that those trees provide fewer benefits for wildlife. Because mesquite trees can easily cross-pollenate, no tree is guaranteed to be completely seedless (or thornless).

Fully-Grown Size

The size of a mesquite tree depends on the species, the location (and elevation) where it is planted, and how much water it receives.

In higher elevations, mesquites grow shorter and more like shrubs. Similarly, if a mesquite doesn’t receive a lot of water, it is more likely to remain short and shrubby.

In most Phoenix and Anthem area locations, however, mesquite trees can grow to their full expected height, providing either dappled or full shade to the surrounding area.

Because of the smaller size of residential yards, mesquite trees can become a problem simply because they don’t have enough room to grow, nor enough room for their expansive root systems.

Always keep in mind the full-grown size of any tree before you plant it on your property.

Drought-tolerance

As mentioned before, native mesquite trees are very drought tolerant, in part because of their long lateral and tap roots. They will drop their leaves to conserve energy if needed, and their slow-growing nature when water is scarce ensures that they can survive in our harsh desert climate.

Because of this ability to survive in extreme conditions, mesquite trees have become invasive in some areas. In fact, they are considered “one of the world’s most problematic invasive species” in parts of Africa, Asia, and Australia. They have also taken over many pasturelands and grasslands in Texas. This may be why they are referred to in those places as “trash trees” or even “devil trees.”

Remember, any plant or tree grown outside of its native environment has the potential to become destructive or invasive, crowding out native plants. So, while mesquite trees are a needed and vital part of the desert southwest, elsewhere they can become a nuisance.

The fact that mesquite trees require little or no irrigation means that they can easily survive in these non-native locations, where their long roots often steal water from other plants or crops. These long roots mean that mesquite trees can be hard to remove from an area, and the prolific seeds make eradication difficult. When trying to grow a crop, this can become increasingly problematic.

Isn’t it interesting how one of the things that make mesquites best-suited for the Phoenix and Anthem areas makes it problematic for other areas of the world?

Flowers or Catkins

Mesquite trees have “perfect” flowers, meaning that they have both male and female parts. The flowers are often light yellow or white catkins, which later develop into the seed pods.

These flowers can be a signal of changing seasons. For example, when mesquite flowers appear (usually in late spring), they are a signal to vegetable gardeners to plant their warm-season crops.

These small flowers attract many types of pollinators. Bees are often purposefully introduced to mesquite trees to create mesquite honey.

Is planting a mesquite tree on your property a good idea?

We love our native mesquite trees and enjoy seeing them in our community. We even mentioned them in our blog post about the best shade trees for your yard.

However, not all trees suit all yards. If you don’t have a large property, are worried about invasive roots, or think that the thorns or seed pods would pose a problem, then a mesquite tree probably isn’t for you.

But if those aren’t concerns for you, then go ahead and plant a mesquite! Mesquite trees are an important part of the desert southwest and provide food and shelter for a variety of birds and other wildlife. They also provide shade, food, and ornamental interest for local residents.

We hope you have enjoyed learning about one of the most important types of trees in the Anthem and Phoenix areas!

 

 

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