Invasive Plants

When we talk about “invasive” plant species, we’re talking about hostile proliferation of plants that actually do harm to the local ecosystem. Many people have the mistaken belief that as long as it’s natural and growing that plants are not harmful. This is not the case and local plant ecology can be affected similarly to how invasive animal species can damage habitats that they do not belong in.

Read more about invasive plants and animals at the Arizona Sonora Desert Museum Invaders website.

The Sonoran Institute and the National Park Service with funding from the AZNPS-Tucson Chapter has produced Fact Sheets for 74 Invasive Exotic Plants which include morphologic descriptions, photos of plant parts, ecology and distribution maps. A description of the project is explained here. For an example of the fact sheet for Sahara Mustard, Brassica tournefortii, click here.

Threatening Species

These are the current most threatening plants that are currently considered invasives to native Arizona ecosystems. Currently, Buffelgrass (Pennisetum ciliare) and Fountain Grass (Pennisetum setaceum) are spreading through the Sonoran Desert and threatening our distinctive native Sonoran Desert plants.

Buffelgrass (Pennisetum ciliare)

Buffelgrass is a fairly large, ragged bunchgrass that was introduced to Arizona from Africa for cattle forage. The linear leaves are brown in winter and green in summer, when it produces tan to brown seed heads containing many small bristles. These heads produce large numbers of wind-dispersed seeds, which establish easily on roadsides, vacant lots, alleys, and even in remote parts of the desert. Established buffelgrass forms large and dense colonies that persist and increase.

Buffelgrass looks dramatically different depending on whether it is green and actively growing or dry and dormant. Download this information sheet to identify buffelgrass when it is dry.


Fountain Grass (Pennisetum setaceum)

Of the many threats to our native plants and animals, the spread of invasive nonnative species is a great concern. When they invade new areas, they can displace native plants and animals as they compete for ground surface, sunlight, moisture, and nutrients. They can cause drastic changes in the landscape and can affect the entire ecosystem. Invasive grasses tend to provide fuel for fires that destroy the natives. This flyer is one in a series, describing problematic invasive species and telling you what you can do to help save our Arizona desert.


Stinknet (Oncosiphon piluliferum)

A recent and concerning arrival to Arizona is Stinknet (Oncosiphon piluliferum or Globe Chamomile). This plant is spreading rapidly in both urban and wild areas and can quickly dominate a landscape. This little winter annual (6-24 inches) has only recently been recognized as a prolific invasive weed in the Phoenix Metropolitan area and elsewhere in Arizona.

The weed has spread from severe initial infestations in Northwest and North Phoenix into metropolitan Phoenix and is now spreading into Southern Arizona.

Stinknet is a fast moving invasive in Arizona!

Additional Resources

The Pima County Department of Natural Resources, Parks and Recreation has trained volunteers to help neighborhoods recognize the threat. To schedule a Buffelgrass Educator for your neighborhood, contact the Pima County Environmental Educators by email or call 520-615-7855.

Gather your neighbors and friends to clear out these invasives that threaten neighborhoods, natural landscapes and scenic roadways in Pima County. Go to Pima County Roadway Invasive Weed Removal Program to download forms and guidelines.