Water hyacinths are any of the species of aquatic flowering plants in the taxonomic genus Eichhornia. It has strong resistance and tolerance to survive in highly polluted circumstances making it one of worst weeds in the world. It has soft, bulbous stalks like a bladder and this allows it to float on the water easily. It has dark, glossy leaves, purple petals, and a fibrous root system. It uses root hairs to absorb the nutrients and minerals in water. The plant reproduces both sexually and asexually, but budding and stolon reproduction is more common. They produce the daughter plants and it can grow into individual plant. It is distributed all over the world, but the origin started in the Amazon River of Brazil.
Because of its invasive nature, the water hyacinth is prohibited in some countries. It destroys the ecosystem of native species because it blocks the water currency, sunlight, and nutrients. It covers the water and takes all of the nutrients and minerals in the water, which leads to the extinction of other plants. It is also toxic to animals and people. It provides a great habitat to mosquitoes, snails, and bacteria. It requires careful treatment for the water hyacinth, not to increase uncontrollably. 
The water hyacinth is a floating plant living in water. It can grow to a height of 0.5 m. It is constructed with a very supportive structures that has piles of brown roots and the hairs around it suck up mineral, salts, and water which is essential to the plant.
Rosettes of rounded and leathery, glossy green leaves makes the water hyacinth easily recognized. They can grow up 2 to 15cm long and 2 to 10cm wide. The leaves are dark green colored, but glossy, waxy, and shiny. Also, they let the plant catch the wind which helps it to float on water to make a new colony. The leaves are densely veined and either suborbicular, ovate, or elliptic. They attach to thick, spongy and bulbous stalks. Inside of its unique swollen bladder-like stalk, it is really soft, and it provides another method to float for water hyacinth. With the light, soft bladder-like stalk, the buoyancy to float increases. It can grow up to 50cm long. 
Also dark feathery roots and lavender flowers are the other characteristics of the water hyacinth. The roots are fibrous root system and they are heavily branched, hidden underneath the water. They dip into the water for 2 to 3 inches and live on nutrients in the water.
The flowers of water hyacinth contain six stamens with curved filaments and a spike can feed 8 to 25 flowers.  They can tint with light blue or violet and sometimes the yellow patch appears on the uppermost petals. The highest petal usually has the yellow patch, while others are pale violet. The perianth tube can grow 15 to 20mm long and the lower bract forming a blade. 
The water hyacinth is capable of sexual and asexual reproduction, and both methods are necessary to make more offspring. During the sexual reproduction, water hyacinth makes lots of seeds that each of 25 flowers on a spike makes it. Then, there is an abundance of seeds spreading to reproduce. Birds helps to spread the seeds and they stay dormant until the flooding helps it to germinate. The germination occurs in wet soil that provides moisture to the plant. It can live about 15 to 20 years after germination. The reason how water hyacinth can live long is that it easily adapts to extreme environments. It is affected by pH level, temperature, toxic water, or nutrient supply only a little bit. It is easy for water hyacinth to spread the offspring with strong adaptation. Especially, E. crassipes makes a thin walled, capsule-like fruit. It is surrounded and protected. Also, every capsule has ability to contain about four hundred-fifty 4-mm long x 1-mm thick seeds. However, the reproduction still happens more effective in mild climate and saturated soils with slow-moving water.
For asexual reproduction, it uses budding and stolen production, and it is a more common way to reproduce asexually. The rosettes breaks into little individuals and the daughter plants germinate from the stolons. Sometimes they struggle during droughts, but they restart the growth cycle with reflooding and germination.
During the spring to winter, the asexual reproduction occurs more often. It produces more daughter plants gradually in both size and number til September. When there is abundance of plants, it starts to die and new colonization begins again.
Eichhornia crassipes is native to the Amazon Basin of Brazil, but now it is introduced to almost the whole world: Central America, North America, Africa, India, Asia, Australia, and New Zealand. In the US, it is observed throughout the north to Virginia and west to Texas, and also seen in Hawaii, California or other states. People believe the water hyacinth has come into US during the [[[World's Industrial]] and Cotton Centennial Exposition of 1884-1885 in Louisiana. Then, it spreads out through St. Johns River to whole the country with its strong propagation. 
Water hyacinth can grow in lakes, streams, ponds, waterways, ditches, or backwater areas anywhere water is available. However, it still prefer water with more nutrient and minerals.
In its native land, the Amazon, the Water Hyacinth feeds the natural predators that limits the growth of it. However, it is known as a noxious weed commonly. Some people describe the plant as the worst plant in the world that it invades the native flowers and plants. For example, in Florida, the water hyacinth alters the natural cycle of the plants. It removes the native species and dominate the land, changing the the structure, composition, and the community. If the water hyacinth densely dominates the region, the quality of water can be worse that it takes all the nutrients in water and blocks the other plants to grow.
The reasons for its widespread population are its effective and easy reproduction and wind movements. As it can reproduce asexually to divide itself into two or several daughter plants. Also, it floats on the water and that allows it to move by winds. The winds makes a current in water and the water hyacinth will wander, following the water and wind currents.
However, often it provides a benefit to the other animals. Its fibrous root system can be a habitat for insects and some coots use leaf blades and petioles.
As the water hyacinth is known for noxious plant, it is difficult to kill. It can tolerate serious pollution and can cover the whole water if not controlled. It prevents the water current and degrades the water quality by reducing the nutrients and amount of oxygen in the water. It will be difficult for the native species to get sunlight, because the water hyacinth blocks it.  It also affect the agriculture to block irrigation canals and destroy the fields. As it takes every things beneficial to them, the native species can not feed themselves and will disappear. However, there will be a nice place for the mosquitoes and bacteria to live when the water hyacinth flourishes. Some gold fish can be also be fed by it.  For instance, arsenic has been spread over the environment to destroy the water hyacinth, but the result was poisoning only the ecosystem. It can grow quickly if there is a little, tiny part of fragment with asexual reproduction, so arsenic could not stop this fast-growing plant. Moreover, fire and explosives could not destroy the plant absolutely and even failed to decrease its number. In Singapore, it has brought a problem in reservoirs that it disturbs the fluency of them, while it has been used for pig food. The only way to control the water hyacinth is by natural process, and a moth, fungi, fish, and manatees can limit its dramatic growing number. 
Bioremediation by water hyacinth
As water hyacinth has strong resistance to pollution and can spread quickly in any hard situations, it starts to be used in wastewater treatment. It removes organic pollutants and even the plant's fibrous root system to provide extra shade to fish and invertebrate hiding from predators. Some people in Bangladesh use it as a fertilizer in agriculture.
How to control water hyacinth
The Water hyacinth is an invasive, toxic weed that can be fatal to cats, dogs, and horses. These animals will suffer with the symptoms of vomiting, or anorexia.  It even has possibility to cause skin rash to some. It has really strong resistance that it can uptake some metals like Cd, Cr, Co, Ni, Pb and Hg.  Moreover, highly poisonous substance, cyanide can be affected by water hyacinth.
When water hyacinth appears in the pond, it can double its number within 2 weeks that people need to concern of it and take actions quickly. It will hold the water currency and make a habitat for mosquitoes and other unfavorable insects. 
- Bring domestic geese into the pond. According to the research, geese can at least control the excessive number of water hyacinth. However, they can not solve the root of the problem.
- Use endothall dipotassium salt. It is a good idea to use herbicide to prohibit water hyacinth's negative effect to the aquatic ecosystem.
- Pick up the invasive water hyacinth. It is effective with a little pond, but it may be hard for bigger places.
- Replace water hyacinth with water lilies.
- Get help from natural predators. For example, the studies show that Neochetina weevils and the Sameodes albiguttalis moth is effective to limit water hyacinth. 
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