You are probably familiar with food going bad, but what about a weed going bad? What does that mean? ‘A weed gone bad’ refers to a weed that is growing out of control for some reason. It may be a very fast grower that has found a perfect environment with lots of nutrients. As a result, such a weed could grow so fast that would grow faster than any other plants around it. It the end, it would smother the other plants by sheer number! When a weed goes bad like this, it is also bad for the environment. Why? Because in order for different types of animals to live in an area, there must be many different types of plants for them to eat. This concept is called biodiversity. Without biodiversity, nature as we know it would be very different. It wouldn’t be filled with a lot of different birds, animals, insects, and plants at all. Instead, only a few different organisms would exist.

There are a lot of different plants (and even animals) that can take over their habitat (where they live). Sometimes organisms are introduced to an area where they don’t normally live. In their normal habitat, their growth is kept in check by other organisms (they may compete with them for space or nutrients, or they might eat them) or tough living conditions. But in a new habitat, they may no organisms that can keep their number in check or the living conditions might be perfect for them. This could spell big trouble for the other organisms that live there.  

People in the southern USA have been finding that out first hand, thanks to the recent invasion of what scientists call “the world’s worst weed!” This weed is a waterweed that normally lives in freshwater in Brazil, in South America. It is called giant salvinia, which is sort of a funny name as it is actually a tiny fern. This fern is kept in check in Brazil by a bug that likes to eat it. But in 1995, the weed hitched a ride with a cargo ship to South Carolina, and it has been heading west ever since! In the US, it grows like crazy, because there are no bugs that eat it. If just one plant enters a body of water in the US, there will be up to 60 million plants in a few months! Quickly, it forms giants green mats that float on top of the water and shade out all the plant life below. Animals and insects that eat these plants soon die as well. Hence, the world’s worst weed is the southern states’ biggest pain in the neck! One answer to the problem is a massive people powered weed clean up that could go on for ages! Either that or find a bug that likes to eat it. But introducing another new organism could just cause the same kind of trouble!