The water hyacinth is a foreign weed introduced in the early 1990s to Nigeria. Since then it has spread rapidly to two-thirds of the country's rivers.
It has caused immense damage to livelihoods of boatmen and fishermen as it blocks waterways and sunlight to aquatic life.
But despite its bad reputation, some scientists have discovered other ways it can be put to good use.
Al Jazeera's Ahmed Idris reports from Lagos.
