Common Name: pampas grass
Scientific Name: Cortaderia jubata
Code: COJU2
Group: Monocot
Family: Poaceae
Growth Habit: Graminoid
Duration: Perennial

What does it look like?

Pampas grass is a tall, attractive grass, often used in ornamental gardening. It grows in large clumps, six to twenty-three feet tall with large, flowering plumes at the end of long stems. The plumes consist of hairy female flowers that are deep violet when immature and silvery-white or pinkish at maturity (Bossard et al. 2000).

Where does it grow?

Andean pampas grass is native to South America and is now abundant throughout coastal California. It is especially apparent growing along roadsides and hillsides in the coastal town of Trinidad in Humboldt County.

Pampas grass grows only in coastal areas in bare, disturbed soils such as roadsides, cutbanks, dunes, coastal bluffs, rock outcrops, landslides, and logged areas. It cannot survive under the shade of a forest.

Is it in our watershed?

Though not yet a widespread problem in the Mattole, pampas grass has been spotted in several locations throughout the watershed, including Petrolia, the Mattole estuary, and a few sites along the Mattole Road. This species should be eradicated before large-scale infestation occurs.

Why is it a problem?

This species is an extremely aggressive invader that quickly crowds out native coastal dune, hillside, shrub and estuarine vegetation. It produces millions of seeds without pollination (NPS 2001).

How do you get rid of it?

The most effective method of controlling this species is to eradicate it BEFORE it sets seed.

Manual Removal: Pulling or digging up young pampas is most effective, and easiest in moist soil during winter and spring. If plumes are present, carefully place plastic bags over the plumes and THEN cut the stems. The seeds have short viability and will die within a few days, but it is still important to dispose of the plumes carefully. If the rootwad cannot be removed, it is best to annually remove the plumes to control their spread (Sabrina Stadler, pers. comm.). Removing mature plants by hand is difficult, but it is possible to cut the stems using a pulaski and shovel and dig up the root ball and remove it from the ground. If removal of the root ball is not possible, chop and then cover it with black plastic for six months (BLM 2003).

Mechanical Removal: An easier way to remove mature plants is to place a choker cable around the base and pull it out with a winch. (Note: If the choker slips off, dig around the base for a better grip.) Turn the plant upside down after removing so roots do not touch the ground. Make sure to conduct post-removal monitoring and if the plant is unable to take root again, it will die. Backhoes can remove larger plants.

Revegetation with fast-growing native trees can produce enough shade to keep pampas grass from returning (NPS 2001). Educating people on the ecological concerns of invasive exotics is extremely important in controlling Andean pampas grass invasions in California. Its plumes often attract people (especially children) to cut and wave them around, attaching seeds to bicycles and car antennas. This spreads seeds rapidly and ubiquitously.

Author:
Unity Peterson, Invasive Plant Program Coordinator, Mattole Restoration Council, Petrolia, CA.

Photograph:
Unity Peterson

References:

BLM. 2003. Noxious Weeds of the Arcata Field Office. Bureau of Land Management, Arcata Field Office, Arcata, CA. http://www.ca.blm.gov//arcata/arcweeds.html

Bossard, CC., J.M. Randall and M. Hoshovsky. (eds.) 2000. Invasive Plants of California’s Wildlands. University of California Press, Berkeley, CA. Online version:
http://www.cal-ipc.org/invasive_plants_of_california's_wildlands/

NPS. 2001. Exotic Plant Species List: Scientific and Common Names of Known Exotic Plant Species in the Redwood National and State Parks. National Park Service (last update: June 13, 2001). http://www.nps.gov/redw/epsplist.htm