"Each year that intervention is delayed makes the problem more expensive, more difficult and practically impossible to stop," warned Hélia Marchante, professor at the Higher School of Agriculture of the Polytechnic University of Coimbra and specialist in invasive plants, in a press release sent to the Lusa news agency.

Plant identified

According to the professor and researcher, a study carried out in 2025 on the distribution of invasive plants in mainland Portugal identified the plant, whose scientific name is 'Cortaderia selloana', in 208 municipalities - "but it is possible that it is in more" - placing it among the ten invasive plants with the widest distribution in the country.

“We are not facing a future threat. The invasion is already underway. And it is advancing rapidly. The problem is not a lack of knowledge. It is a lack of action on the necessary scale. Portugal has known for years that Cortaderia selloana is an invasive species,” he emphasised.

The plant in question is known for its showy plumes and is frequently seen by roadsides, in coastal areas and on riverbanks, but also on private property - “planted in gardens and placed in pots” - or in parks and public spaces owned by municipal councils, parish councils and other entities.

Portuguese legislation

According to the note, a 2019 decree-law (seven years old) established the national regime for the prevention and management of invasive exotic species, including “expressly Cortaderia selloana in the National List of Invasive Species”.

“The legislation prohibits, among other things, its possession, cultivation, trade, transport and use as an ornamental plant and determines the adoption of appropriate management measures. More importantly, the legislation itself establishes an unequivocal logic: prevent, detect early and act quickly,” stressed Hélia Marchante.

Citing several articles of this legislation, the scientist and head of the “LIFE COOP Cortaderia” project at the Higher School of Agriculture of Coimbra – which involves institutions from Portugal, Spain and France in the fight against this invasive species – stated that a surveillance system is foreseen, as well as the immediate communication of new occurrences and that invasive plants in national territory “should be the subject of action plans for control, containment or eradication, with priorities defined according to the severity of the threat and the difficulty of intervention”.

The Institute for Nature Conservation and Forests (ICNF) has the action plan for the control of Cortaderia practically ready, but its publication and, more importantly, its implementation, stubbornly refuses to happen,” accused Hélia Marchante. “Science says to act early. Legislation says to act. International experience shows that waiting makes everything worse. So why do we continue to see the expansion of Cortaderia? (…) Every plant that is allowed to produce seeds is a factory for new invasions.”

Environmental health problem

Other studies warn that the species could pose an environmental health problem, potentially affecting human health, given the allergenic nature of its pollen.

On the other hand, due to its late flowering, an exotic species like Cortaderia, from South America, could create, especially in Mediterranean regions, a second season of exposure to pollen in the autumn, “with implications for public health.”

In addition to public entities, to whom they request coordinated intervention – from central administration to municipalities or managers of protected areas, among others – researchers at the Agrarian University of Coimbra recognise the “fundamental role” of citizens in recognising the species and in preventing its use and dissemination, “controlling it in their gardens and land and reporting new occurrences.”

"And a paradigm shift is needed: we cannot continue intervening only where and when corruption already dominates. We have to seek out and eliminate new outbreaks before they become major outbreaks," the institution argued.