Water hyacinth

Description:

Spongy stalks, and oval broad leaves floating on the surface, and often forming floating islands that moves with current. It produces beautiful light blue flowers, some 15 of them on one stem.

Habitat:

Originally from South America, it thrives on shores and lakes in tropical region of Africa. These photos were taken on shores of mighty river Congo - but at the moment its waters were rather low, outside the rainy season.

Notes:

This is a very invasive species, and it is been said, that if not controlled, it can completely cover smaller lakes and shores of rivers. It was also often mentioned (but I could not confirm) that by covering these water bodies, it creates and favors the development of mosquitoes (malaria, dengue) and a species of snail hosting a parasite causing bilharzia.