The invasive fern that science misidentified for decades

Salvinia molesta can double its biomass in 36 hours. It spreads across ponds, lakes and slow-moving waterways in a smothering green mat, blocking sunlight, consuming oxygen and collapsing the ecosystems beneath it. Now present in freshwater bodies across more than 60 countries, it ranks among the top 100 most invasive species in the world. Scientists have long wanted to understand what makes it so relentlessly effective.