The pampas grass ( Cortaderia selloana ) is an invasive species that is cultivated and grown as a decorative plant, often to line roadways and properties. The dried plumes of the flower head are widely used in floral arrangements and sold in craft shops. It has been introduced all over the world with serious ecological consequences. It grows so fast it sometimes chokes out native plants reduces biodiversity and displaces native animal habitats. Pampas grass can grow up to 15 feet tall, but only if given enough water and nitrogen-rich fertilizers. They also produce an abundance of seeds every year which are dispersed by wind, animals or humans to create new colonies along footpaths, roadsides, riverbanks and waterways. The seeds are also sticky so it gets stuck on people or animals passing by.
In California, pampas grass has been listed as a noxious weed in the counties of Contra Costa, Santa Cruz and Los Angeles. It is illegal to sell without a permit. In Florida, all six palm beach county’s have declared pampas grass a “noxious weed” but yet they still continue to grow it illegally and sell it at craft shows and small business owners do not face any repercussions if caught selling or planting this invasive species which kills native plants, damages infrastructure such as roadsides, canal embankments and riverbanks.
Pampas Grass Facts
-Grows wild in the Mediterranean and has become an introduced species in California and Oregon, 3rd and 4th most populous states of America
-Invasive species able to cause significant changes in ecosystems
-Can completely alter plant community structure
-Spreads by rhizomes that grow horizontally below ground or by windborne seeds. In its native range, pampas grass is a fire follower, sprouting from rhizomes after fires have passed.
-Untill now there are no reported cases of allergies due to pollen released by the flowers of pampas grass. However it is possible that people with known allergies to other members in Poaceae family (a grass family) could be effected by pollen of pampas grass. This effect is not documented, however non-documented case does not mean that the risk doesn’t exists.
-Flowers are pollinated by insects and hummingbirds.
Why should we care? Pampas grass can be very dangerous for ecosystems where it takes root. It is highly invasive species, capable of altering plant community structures by forming homogenous stands on large areas. Growing rapidly in height (up to 8 meters) it outcompetes other local plants while producing abundant amounts of litter on the ground that affect soil properties, change nutrient cycles and increase fire frequency/intensity.
-Local fauna might suffer too. Some rodent species that feed on seeds of pampas grass are highly affected due to the loss in availability of food source.
-Australia has already felt the negative effects of introduction of pampas grass, where it has spread over more than 1 million hectares.
-The Australian government spends large amounts each year in an attempt to contain its further spreading.
-Pampas grass is not native to California or Oregon. Despite this, we see them growing wild and abandoned all around these states without any attempts to try and eradicate them even though they pose serious threats to local ecosystems. Even if most part of its habitat in these states is usually located in private lands, state and local should contribute and allocate money for an effective eradication campaign.
-We don’t know how much it would cost to actually eradicate pampas grass from California and Oregon. However we can give an estimation using Australia as an example: “For over 20 years, the Australian Government has been spending $2 million AUD per year trying to control and eradicate pampas grass.