Invasive Desert Landscape Plants (Do Not Grow!)

Anyone who has lived in the southwest for some time has heard about invasive plant species such as buffelgrass and stinknet. But there are several landscape plants, including some extremely popular ones, that have been found to be invasive, too.

The invasiveness of plant species such as buffelgrass (Cenchrus ciliaris) and stinknet (Oncosiphon pilulifer) is no secret. But there are several landscape plants that have been found to be invasive, too.

First, let’s take a look at plants known to be invasive in the desert southwest. Then we’ll discuss plants that are considered “potentially invasive.” Most are already growing aggresssively and considered invasive in neighboring states.

The Problem with Invasive Species

For a plant to be considered an invasive species, it must meet two criteria.

It must be non-native.
It must cause harm — to the environment, animals, people, or the economy.

Most invasive species were intentionally introduced for some perceived attribute or benefit. The unintentional harm usually took some time to manifest and be discovered.

Here are some of the problems caused by invasive species in the desert southwest:

They grow fast, spread prolifically, and are free of forces that keep them in check in their natural range. They readily out compete native plants, leading to reduced biodiversity.
Dried grasses create fuel for wildfires. As they dry out, they become extremely flammable. They burn hotter than native grasses and rebound from fire faster, too. This enables them to out compete native species.
Those that grow near water block the natural flow of water in washes and alter the habitat for animals.
Invasive species rarely provide benefits to native wildlife or pollinators.

Buyer Beware!
Unfortunately, most garden centers
sell plants & seeds known to be invasive.

Popular Landscape Plants Considered Invasive

Here are some of the worst desert landscape plants that have turned out to be invasive. These plants grow unchecked, wreaking havoc on desert ecosystems.

Fountain Grass

Fountain grass (Cenchrus setaceus) is a perennial bunch grass native to Africa. It was first brought to the desert southwest around 1880 to prevent erosion. In the 1940s, it was introduced as an ornamental plant. Within a few years, it started invading the Santa Catalina Mountains.

Fountain grass is closely related to buffelgrass (Cenchrus ciliaris), a highly invasive grass the National Park Service calls “the archenemy of the Sonoran Desert.”

Fountain grass was officially listed as an Arizona Noxious Weed in 2020 and consequently can no longer legally be sold in nurseries.

Purple Fountain Grass

However, that ban does not apply to purple fountain grass (Cenchrus setaceus ‘Rubrum’) which you can still find at most nurseries and big box garden centers. This is unfortunate, because its sterility has been exaggerated and plants can still disperse viable seeds which grow outside of cultivation.

Organizations that acknowledge the purple variety is invasive include the Desert Botanical Gardens, the Arizona Native Plant Society, and the National Park Service.

Alternatives to consider: deer grass (Muhlenbergia rigens), pink muhly grass (Muhlenbergia capillaris), big muhly (Muhlenbergia lindheimeri)

Pampas Grass

Pampas grass (Cortaderia selloana) is a large, dramatic ornamental grass with unmistakable huge white plumes. This South American native is planted often here in Tucson, but it may be common where you live.

The University of Arizona considers it an invasive species. It has escaped into the wild in several Arizona counties — Coconino, Yavapai, Maricopa (Phoenix), and Pima (Tucson).

The National Parks Service reports invasive pockets at Glen Canyon National Recreation Area (UT) and
Grand Canyon National Park (AZ). It’s also considered invasive in California.

Oleander

Oleander (Nerium oleander) is a highly popular and attractive shrub with a large natural range that extends from the Mediterranean to Myanmar. It’s prized for being fast-growing and resilient, for flowering profusely, and for requiring minimal care.

It’s main drawback, its toxicity, is well-documented. But the fact that it’s considered invasive in Arizona and other parts of the southwest is a lesser-known issue.

The US Forest Service reports that pockets of invasive oleanders have been found in Tonto National Forest (near Phoenix) and Saguaro National Park (near Tucson).

The US National Park Service has reported invasive oleanders in Lake Mead National Park (NV) and even in one of the least hospitable places in the country — Death Valley National Park (CA).

The Arizona Native Plant Society has found oleander growing in Bear Canyon in the Catalina Mountains.

The non-profit organization WildArizona.org is is monitoring Arnett Creek and Telegraph Canyon, just outside of Superior, AZ for oleander which has “infested these canyons, impacting native plant populations, and reducing available surface water.”

You can see a map of this plants’ distribution at InvasivePlantAtlas.org.

Alternatives to consider: Arizona rosewood (Vauzuelinia californica), Texas olive (Cordia boissieri), hop bush (Dodonaea viscosa)

Tree of Heaven

Tree of heaven (Ailanthus altissima) is a fast growing deciduous tree originally from China. It was introduced to the US via Europe in the late 1700s. This plant is so tough it can grow out of cracks in pavement.

It has everything an invading plant needs to succeed. It produces seeds prolifically. (One tree can produce up to 350,000 seeds in a year.) It sprouts and resprouts aggressively even from cut stumps. It produces allelopathic chemicals that prevent nearby plants from growing.

The National Parks Service has found tree of heaven to be invasive in numerous national parks across the country including in Death Valley National Park (CA), Yosemite National Park (CA), and Grand Canyon National Park (AZ).

Alternatives to consider: Arizona ash (Fraxinus velutina), red push pistache (Pistacia x ‘Red Push’), feather tree (Lysiloma microphylla)

Potentially Invasive Desert Landscape Plants

This next group of plants is not considered invasive in the southwest… yet. There are plenty of reasons to avoid planting these, too, since today’s invasive species were yesterday’s “potentially invasive” species.

Most are invasive in neighboring states and the experts agree that they have the potential to become invasive here.

Since there are always native look-alike alternatives, I would err on the side of caution and choose one of those instead.

African Daisy

African daisy, (Dimorphotheca sinuata), also known as cape marigold, is a cheerful South African low-growing annual that’s easy to grow from seed. It has a habit of readily reseeding vigorously and can be see blanketing yards and large swathes of open land in the spring.

It has escaped cultivation and naturalized in Arizona and California. The National Park Service reports African daisy as invasive in Saguaro National Park.

But there’s some debate as to whether it fits the criteria of being invasive, since it has not been established whether this plant “does harm.”

close up of orange african daisy flowers — African daisy

Until this issue is resolved, I would grow one of the similar-looking native poppies instead.

Alternatives to consider: California poppy (Eschscholzia californica), Mexican gold poppy (Eschscholzia californica ssp mexicana), Arizona summer poppy (Kallstroemia grandiflora)

Note that Dimorphotheca sinuata is often confused with another plant called African daisy that’s in the Osteospermum genus. Osteospermums are often sold as potted plants that come in a rainbow assortment of flower colors.

Cat’s Claw

Cats claw (Dolichandra unguis-cati) is a vine of choice for covering unsightly cement block garden walls since it grows fast, needs little water, and clings to walls without support. It doesn’t mind reflected heat and can be grown directly on the hottest walls on your property. It is undoubtedly aggressive and nearly impossible to get rid of once established.

Its native range covers much of South America and includes Mexico, making it a near-native to the desert southwest.

Cat’s claw is considered invasive in many parts of the world. (It’s a serious scourge in parts of Australia.) It’s considered invasive in Texas and there’s evidence that it has the potential to become invasive in Arizona.

Alternatives to consider: yellow orchid vine (Callaeum macropterum), Carolina jessamine (Gelsemium sempervirens)

Mexican Feather Grass

Mexican feather grass (Nassella tenuissima) is an ornamental grass that’s delicately beautiful, a description that rarely applies to desert plants. But this grass is much tougher than it looks. Each plant produces tens of thousands of seeds, which are dispersed by wind, water, and animals.

Its natural range only includes the mountains in west Texas and adjacent New Mexico, but according to the Lady Bird Johnson Wildflower Center, it has the potential to become invasive throughout the southwest.

Arizona State University also acknowledges that Mexican feather grass has the potential to become invasive, particularly in the grasslands of Arizona.

It’s currently considered an invasive species in California, especially in the southern part of the state and in the San Francisco area.

Alternatives to consider: sideoats grama (Bouteloua curtipendula), bull grass (Muhlenbergia emersleyi)

Yellow Bird of Paradise

Yellow bird of paradise (Erythrostemon gilliesii) is a large, airy shrub with fern-like leaves and stalks of yellow flowers from spring through fall. Plants are often pruned to grow as a small tree. It is native to the deserts of Argentina and Uruguay but has naturalized around the world.

In the US, it has escaped cultivation in these southwestern states:

California
Arizona
Nevada
Utah
New Mexico
Texas

In Arizona, it can be found growing along roadsides and in other disturbed areas. The University of Arizona has labeled it as invasive.

Alternatives to consider: Mexican bird of paradise (Erythrostemon mexicanus), cascalote (Tara cacalaco)

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Author Bio

Deane Alban is the creator of Southwest Gardener. She is a science writer with a bachelor’s degree in botany from the University of South Florida. Gardening is her lifelong passion. She’s been gardening in Tucson for 15 years.

Read her full bio