Fountain Grass (Pennisetum setaceum)

Fountain grass is a robust clumping grass that grows up to 3 ft. tall and wide. Its long, wiry leaves are 11-30" long from the base and form dense, light green clumps. Together the white or purple-tinged inflorescences form a halo above the green leafy core. The cylindrical inflorescences are thick, 4-14" long, round in cross-section, pink, or purplish during colder weather, and dry white. Soft silky hairs to over an inch long surround the fruits. This grass grows most vigorously in the warm season (July to September), but also flowers most of the year below 3,000 feet in our region.

Close ups of fountain Grass heads
Photos: Julia Rowe

Why is it a threat?

Each fountain grass plant produces thousands of highly-viable seeds, allowing it to spread rapidly from cultivation into nearby disturbed areas, and eventually into natural habitats. It often forms dense stands and aggressively competes with native species, especially perennial grasses and seasonal annuals, for space, water, and nutrients.

Fountain grass provides ample fuel, and is well-adapted to fire. When it burns, it re-grows rapidly from extensive roots. It is important to note that fire is not a prominent ecological process in the Sonoran Desert; native plants, including iconic saguaros, are not general fire-adapted.

Threats from fountain grass fires are most serious in natural riparian habitats in scenic mountain canyons. In the Tucson area, it has invaded the rocky canyons in Finger Rock, Pima, Sabino, and other canyons in the Santa Catalina Mountains and King Canyon in the Tucson Mountains.

Fountain Grass growing among rocks
Photo: Julia Rowe

It has been declared as a state noxious weed by Arizona, Hawaii, and Nevada.

Control

Small infestations of fountain grass can be controlled by physically removing the entire plant, including the seed-bearing inflorescences. Seedlings and small plants can easily be pulled by hand. Iron digging bars or shovels will help extract larger plants. It may be necessary to return to controlled areas for several years to remove seedlings. Chemical treatments with systemic herbicides may be needed to control large infestations. Herbicides have been sprayed from boats to control fountain grass along rocky shorelines of Colorado River reservoirs.

There are a wide variety of native grasses that can be used in urban landscapes, including bullgrass (Muhlenbergia emerselyi), deergrass (Muhlenbergia rigens), and Arizona cottontop (Digitaria californica) to name a few. Beargrass (Nolina microcarpa) and desert spoon/sotol (Dasylirion wheeleri) are native succulents that grow in large clumps that are attractive in desert gardens and road medians. Another interesting alternative is desert milkweed (Asclepias subulata); its attractive, upright form and low water use make it a xeriscape favorite, and it provides resources for monarch butterflies!

Distribution

Fountain grass is native to North Africa and the Middle East. It has been widely cultivated as an ornamental around the world and often escapes into natural habitats. In the United States, it is common in southern Arizona, southern California, southern Nevada, southwestern Utah, and Hawaii. It has also been found in Florida, Louisiana, Tennessee, Oregon, Colorado, and Texas.

In Arizona it is widespread in the Phoenix, Tucson, Ajo, and Gila Bend areas in Maricopa and Pima counties. It is also common along the Colorado River from Lake Mead to Parker in Mohave and La Paz counties. A few plants have also been found in Cochise, Gila, Pinal, Santa Cruz, and Yavapai counties.

Fountain grass thrives on disturbed roadsides, rocky outcrops, canyons, and cliffs from 2,000 to 3,500 feet in the Sonoran Desert Region in Arizona. It is most common in riparian habitats within paloverde-saguaro desert-scrub in the Arizona Upland Sonoran Desert. It is less common in the Lower Colorado River Valley desert-scrub down to about 985 feet, and in chaparral, desert grassland, and oak woodland up to 4,800 feet. On the north side of Tucson, it replaces buffelgrass on roadsides and rocky road cuts.

It is also common in another riparian habitat on flood lines and rocky shores of reservoirs and rivers in low-elevation (400 to 1,200 feet) Mojave and Sonoran desert-scrub. It is common from Lake Mead to Parker along the Colorado River in some very hot, dry areas.

History

Although fountain grass was reported in Hawaii as early as 1914, it was first collected on roadsides in Arizona in the Santa Catalina Mountains (4,500 ft. elevation) and in Ajo in 1940. It was used in urban landscapes in Tucson as early as 1940, and cultivated in the Soil Conservation Nursery (now National Resource Conservation Service) in 1941. It was well-established in the Santa Catalina Mountains by the 1940's and the Phoenix area by 1962. Later specimens were collected in now-protected natural areas in the Tucson area including Tumamoc Hill (1968), the Arizona-Sonora Desert Museum (1966), and King Canyon (1988) in the Tucson Mountains, and Sabino Canyon (1974) in the Santa Catalina Mountains. Like buffelgrass, it has expanded dramatically in many areas since 1990.

Links

References

Tellman, Barbara (ed.) 2002. Invasive Exotic Species in the Sonoran Desert. University of Arizona Press.

Prepared by Whitney, intern with the Saguaro National Park and SD-CWMA.