Water Hyacinth

Eichornia crassip

World’s Worst Weed!

Water Hyacinth is one of the world’s worst weeds! It can easily take over a body of water in a few years. In fact the body of water that we filmed for this species is located in a dry region of Mexico near Mazatlan. The local rancher said that only two years prior, no vegetation existed in this lake. When we found it, it was completely covered leaving no open water access.
The problem this causes is that it suffocates animals that live in the water. Since these plants respire and use oxygen at night, the concentration of oxygen in the water decreases to a point that little life can exist. The water becomes anoxic.


Water Hyacinth floats on the surface of the water, forming stolons. The plants have a prominent, black, stringy root. Sometimes they grow stranded in mud and will thus appear rooted. The leathery leaves (which are basal) are suborbicular, ovate, and broadly elliptic with parallel veins; the bases are heart-shaped, square, or rounded. The large flowering infloresence is a spike with light-blue to bluish purple flowers. These flowers are very showy. Sometimes they have yellow streaks. The fruit, when produced, has many seeds.

Interesting facts

Biocontrol agents (weevils and a moth) are having a significant impact on water hyacinth populations.

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Written by Rob Nelson

Rob is an ecologist from the University of Hawaii. He is the co-creator and director of Untamed Science. His goal is to create videos and content that are entertaining, accurate, and educational. When he's not making science content, he races whitewater kayaks and works on Stone Age Man.

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