Sometimes, in swamp zones, you happen to see what seems to be a perfectly flat grassland, but in fact it’s no grassland – it’s a body of water completely covered in Lemna minor, the Common Duckweed. A single root and one, two or three floating leaves less than 0.5 cm in lenght, for an organism evolved to reproduce and absorb resources extremely fast. And when I say fast, I mean it, because more than once I kept small containers full of freshwater life for a while to watch it under the microscope, and this species, starting as just a few specimens, always managed to cover the entire surface in just a few days, and I always had to remove the excess. Its secret is that, while it can reproduce sexually through flowers, it mainly reproduces by division (the individuals with more than one leaf originate two or three one-leafed individuals). It is rich in nutrients, and so it’s cultivate to be used as animal food, and it’s also been studied as a way to produce biofuel, but it needs to be harvested very often or its incredibly fast growth allows it to become a pest.