Water hyacinth is a plant that grows chiefly in the tropical regions of the world. It floats on lakes, rivers, and swamps and grows to a height of about 2 feet (61 centimeters) above the water. The water hyacinth has as many as 38 purple flowers grouped around the top of the stem.
Diseases and insects control the growth of water hyacinths in South America, where the plants first grew. But in the Southern United States and other regions where people have introduced the plant, there are no natural controls on its growth. In those regions, water hyacinths are a serious environmental problem because they grow so fast. The plants may double in number every 10 days. They form floating mats that can cover entire water surfaces and destroy the plant and animal life below. Plants need sunlight to live, and fish must have oxygen. The thick growth of water hyacinths blocks the sunlight, and the roots of the plants use up the oxygen in the water. In addition, boats cannot travel on waterways that are choked with water hyacinths.
Many scientists are exploring possible uses of water hyacinths. In the early 1970’s, researchers began the experimental use of the plants to clean up polluted streams. Water hyacinths can absorb many chemicals–including sewage and industrial wastes–from the water in which the plants grow. Thus, polluted water might be purified by passing it through tanks that contain water hyacinths. Other people are studying the possibility of making cattle feed from dried water hyacinths.
