(CNN) — Lake Naivasha, northwest of Nairobi, Kenya is becoming increasingly unnavigable. Water hyacinth, the world’s most widespread invasive species, is blanketing the lake, choking its fish and ...

A lot of people think of plants as pretty to look at, but defenceless and passive as far as organisms go. However, the many alien species – or “monster plants” – around us show we should never ...