Taxonomic name: Pennisetum setaceum (Forsk.) Chiov.
Synonyms: Pennisetum ruppelii Steud., Phalaris setacea Forsk.
Common names: fountaingrass (English), yerba de fuente (Puerto Rico)
Organism type: grass Pennisetum setaceum was introduced to the United States as an ornamental grass. It reproduces high numbers of wind-dispersed seeds that have spread outside of planted areas. Pennisetum setaceum is a desert plant that is prevalent along roadsides, washes and canyons where the annual rainfall is less than 127cm. Pennisetum setaceum interferes with natural fire regimes and competes with native species for limited resources. Description
Benton (1998) describes "Pennisetum setaceum as an attractive perennial grass with a densely clumped growth form and erect stems that grow up to 1 metre high. The small flowers of P. Setaceum are grouped in pink or purple, bristly, upright inflorescences 15-38cm inches long" (inflorescences may also be cream coloured). Fruits are small, dry achenes adorned with long showy bristles.Leaf colouration depends on water availability; in Hawai‘i leaves are typically green in winter and may be brown in summer. Occurs in:
desert, range/grasslands, ruderal/disturbed Habitat description
According to Benton (1998), "Pennisetum setaceum invades many types of natural areas, from bare lava flows to rangelands, in Hawaii. It has a wide elevational range but is limited to areas with a median annual rainfall of less than 127cm. In southern California, P. setaceum invades grasslands, deserts, canyons and roadsides." PESC (2002) writes that P. setaceum is commonly seen spreading along roadsides, washes, and canyons in Arizona. General impacts
Pennisetum setaceum requires full sun to grow vigourously; in dry and open environments fountain grass is a highly aggressive, fire-adapted colonizer that readily outcompetes native plants, it rapidly re-establishes after burning. Fountain grass raises fuel loads, which increases the intensity and spread of a fire, and result in severe damage to native, dry forest species adapted to less extreme fire regimes." PESC (2002) states that these fires create even more space for P. setaceum and other invasive species. "P. setaceum reduce the space available for native species and compete with them for scarce water and nutrients." Benton goes on to say that "P. setaceum is a poor pasture grass and a serious weed in many dry habitats."
In wet areas, however, it is outcompeted by other grasses. Uses
According to Benton (1998), "Pennisetum setaceum has been introduced to many parts of the world as an ornamental grass." Geographical range
Native range: Northern Africa (Benton, 1998).
Known introduced range: The United States including several Hawai‘ian Islands (Benton, 1998); also found on other Pacific Islands, Australia, naturalized in the Canary Islands. Introduction pathways to new locations
Floating vegetation/debris: According to Benton (1998), seeds may be dispersed by water.
For ornamental purposes: According to Devender et al. (1997), P. setaceum is a common landscape ornamental in southern Arizona.
Ignorant possession: According to Benton (1998), seeds may be dispersed by humans.
Road vehicles (long distance): According to Benton (1998), seeds may be dispersed by vehicles.
Transportation of domesticated animals: According to Benton (1998), seeds may be dispersed by livestock.
Local dispersal methods
For ornamental purposes (local): According to Devender et al. (1997), P. setaceum is a common landscape ornamental in southern Arizona.
Garden escape/garden waste: According to PESC (2002), "seeds caught in the base of the plant, can spread after the plant is uprooted.
Off-road vehicles: According to Benton (1998), seeds may be dispersed by vehicles.
On animals (local): According to Benton (1998), P. setaceum seeds are primarily wind-dispersed.
Water currents: According to Benton (1998), seeds may be dispersed by water. Management information
Preventative measures: Planting native species after removal of the invasive will help prevent re-establishment of P. setaceum. Monitoring the area for seedlings and removing them is a good practice as they are easy to pull up when young.
A Risk Assessment of Pennisetum setaceum for Hawai‘i and other Pacific islands was prepared by Dr. Curtis Daehler (UH Botany) with funding from the Kaulunani Urban Forestry Program and US Forest Service. The alien plant screening system is derived from Pheloung et al. (1999) with minor modifications for use in Pacific islands (Daehler et al. 2004). The result is a score of 26 and a recommendation of: "Likely to cause significant ecological or economic harm in Hawai‘i and on other Pacific Islands as determined by a high WRA score, which is based on published sources describing species biology and behaviour in Hawai‘i and/or other parts of the world." Physical: According to Benton (1998), "the long-lived seeds of fountain grass make its control extremely difficult. Small infestations may be managed by uprooting plants by hand and destroying the inflorescences in order to prevent seed dispersal. Removal by hand may need to be repeated several times per year." PESC (2002) suggests removing seed heads to slow its spread. "Since it seeds several times a year, vigilance is required. The only way to prevent future seed production and to reduce the threat of wildfire is to remove all P. setaceum, pulling them up by hand or digging them out with a shovel or crowbar. Disposing of the entire plant after removal will eliminate seeds caught in the leaves at the base of the plant." Chemical: Extensive infestations of fountain grass are probably best controlled with the help of herbicides, especially those with some systemic activity. Reproduction
The white to tan colour seed heads produce large numbers of wind-dispersed seeds (PESC, 2002) [seed set is usually quite low, typically less than 20% = less than 50 seeds per seed head; (Goergen, E., and C. C. Daehler. 2001). Seeds may remain viable in the soil for six years or longer (Benton, 1998). Seeds are produced apomitically. Agamospermy and vegetative propagation are collectively called apomixis. Agamospermy is asexual seed formation Lifecycle stages
According to Devender (1997), “Pennisetum setaceum becomes facultativlely inactive with extended drought, freezing, or near-freezing temperatures.” Reviewed by: Dr Curt Daehler Department of Botany University of Hawaii Honolulu, USA
Compiled by: National Biological Information Infrastructure (NBII) & IUCN/SSC Invasive Species Specialist Group (ISSG)
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Last Modified: Thursday, 23 March 2006
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