Invasive Species, Water Hyacinth

"No one's sure how the South American water hyacinth invaded Africa's Lake Victoria but there's little doubt as to the damages it has caused. In 1989, the weed was spotted in the lake and seven years later, it had clogged 80% of Uganda's shoreline...Rotting vegetation, under the suffocating blanket of weeds, began to foul drinking water — which comes straight from the lake. Meanwhile, along the edges of the floating weeds, water snails harboring the deadly schistosomiasis parasite found a new place to breed." Originally from South America, it is now found in more than 50 countries. Considered one of the worst weeds, people have spread it to most tropical and subtropical regions in the world.