The water hyacinth plant is a flowering, free-floating aquatic plant in the genus Eichhornia. Water hyacinth is fast-growing and produces runners under the surface of the water and a large number of seeds for reproduction. Because of this feature, the water hyacinth plant is often invasive, although many gardeners enjoy its beauty in a controlled environment.
Water hyacinth typically grows to 3 feet in height and 4 feet in diameter. The dark green leaves that float above the water are held aloft by inflated petioles, or stalks that connect the leaves to the stem. Water hyacinth blossoms form on flower stalks and in various shades of blue and violet. Each stalk produces between 8 and 15 individual flowers. Under the surface of the water is a thick, fibrous root system that absorbs nutrients. Multiple water hyacinths form thick mats over the body of water on which they are growing. If left unchecked, the plants can cover the water surface completely.
Water hyacinth grows on bodies of water in tropical and sub-tropical regions. They are primarily found on rivers, ponds, lakes and in ditches. Water hyacinth cannot survive in temperatures below 32 degrees Fahrenheit for long periods, but can recover from short exposures. During times of drought, water hyacinth can root in the mud and survive for several days. The plant, native to South America, was first introduced to the United States in 1884 in Louisiana, and has now spread to 24 other states.
Water hyacinth is grown in ornamental water gardens and ponds for its colorful flowers that extend over the surface of the water. The submerged root system is used as a habitat for both micro and macro invertebrates such as water beetles, snails, frogs and salamanders. These invertebrates are in turn used as a food source by larger reptiles, birds and fish. Once the water hyacinth plant has died, it is quickly decomposed by bacteria. The remaining material, called detritus, is eaten by microbes and other small animals that share the habitat.
Water hyacinth can usually spread over an entire body of water with no supplemental care. Broken or damaged leaves can cause the entire plant to rot if left attached, and should be removed as soon as possible. If water hyacinth foliage begins to yellow, the plant is in need of fertilization. A water-soluble fertilizer should be used following the manufacturer's direction for proper application. If fish are present in the pond, make sure the fertilizer will not affect them before using.
Water hyacinth is extremely invasive and will kill the fish in a body of water if allowed to cover the entire surface. The plant drains the oxygen from the water and the fish eventually die of asphyxiation. It also kills other aquatic plants in the region by using up nutrients and blocking sunlight. Possession and cultivation of water hyacinth is illegal in many states because of these problems. It is also known to clog waterways, especially rivers and streams. Water hyacinth can impede boat traffic by jamming the motor. Water hyacinth chosen for cultivation should be monitored closely to prevent any possible problems.