Cortaderia selloana, known as pampas grass, is an invasive plant native to South America that has already spread across much of mainland Portugal, having been identified in at least 208 municipalities. A study conducted in 2025 placed this species among the ten invasive plants with the greatest distribution in the country. Specialist Hélia Marchante, a professor at the School of Agriculture of the Polytechnic Institute of Coimbra, warns that the problem should no longer be treated as a future threat, since the expansion is happening and could become increasingly difficult and expensive to control.
The plant can be found along roadsides, coastal areas, riverbanks, private land, gardens, and public spaces, and is easily recognized by its large, light, and voluminous plumes. Cortaderia selloana is included in the National List of Invasive Species and Portuguese legislation in force since 2019 prohibits its possession, cultivation, trade, transport, and use as an ornamental plant, although it continues to be seen in gardens and pots.
In addition to the environmental impact on ecosystems, experts warn about effects on human health. Pampas grass pollen has allergenic potential and can worsen respiratory problems in more sensitive people. Because this species blooms later than many native plants, it can prolong pollen exposure during autumn, creating a kind of second allergy season.
Researchers advocate coordinated intervention between central government, municipalities, parish councils, protected area managers, and private landowners. The Institute for Nature Conservation and Forests reportedly has practically completed an action plan to control the species, but experts regret that its implementation continues to be delayed. The public can contribute by identifying the plant, avoiding its use, and reporting new outbreaks.
