Eichhornia+crassipes

toc

=**__Description __**=



The species name // crassipes // is derived from latin, meaning thick-footed of thick-stalked. 1  //Eichhornia crassipes// is  more commonly known as the (common) water hyacinth, is a free floating aquatic plant that generally grows to a height of 0.5m. 2, 3 It can also occasionally be found rooted in soil on banks of water bodies. It has rounded, thick and glossy dark green leaves that are attached to spongy, inflated [|petioles]. 2, 3 The root system lies beneath the water, and is feathery and heavily branched. Its attractive flowers have 6 purplish blue or lavender to pinkish petals, and the uppermost petal has a yellow, blue-bordered splotch in the centre. 2, 3 The flowers grow on a terminal spike in clusters of 8-15. 2, 3

=__**Distribution **__=

The water hyacinth is native to the Amazon basin, but can now be found in more than 50 countries across the tropics and subtropics between 39°N and 39°S. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">4, 5 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> It was introduced outside its native range as an ornamental plant due its beautiful flowers. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;"> 4, 5 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;">The water hyacinth is now considered a highly problematic invasive species outside of its native range, and is ranked as one of the top 100 invasive species in the Global Invasive Species Database. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">2 <span style="font-family: 'Times New Roman',Times,serif; font-size: 12pt;">Due to its invasive nature, the import of water hyacinth has been banned in many parts of the world, such as New Zealand, Australia and parts of the US. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">6, 7 <span style="font-family: 'Times New Roman',Times,serif; font-size: 12pt;">As temperatures climb due to global warming, the distribution of water hyacinth may even expand into higher latitudes where their growth was once inhibited by climatic factors. 4



=__**<span style="font-family: 'Times New Roman',Times,serif; font-size: 14pt;">Habitat **__=

<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Water hyacinth is a perennial aquatic herb that can grow in still or slow-flowing fresh water in tropical and subtropical climates, and even in temperate regions with milder winters. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">8, 9 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> Its optimum growth occurs between 28°C and 30°C, and requires abundant nitrogen, phosphorus and potassium; however, it can tolerate a wide range of growth conditions. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">8 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> It is widely prevalent in tropical and subtropical waters enriched by agricultural runoff, untreated wastes and deforestation. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">10 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> It is especially pervasive in Southeast Asia, the southeastern United States, central and western Africa and Central America due to suitable growing conditions and the lack of natural predators. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">10

=__**<span style="font-family: 'Times New Roman',Times,serif; font-size: 14pt; line-height: 1.5;">Reproduction **__=



<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Water hyacinth is one of the world’s fastest growing plants. It can form dense mats that cover entire bodies of water. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">2, 3, 6

<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">It can can reproduce vegetatively or sexually. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">11, 12 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> However, in many areas, sexual reproduction is rare or even non-existent although flowers and seedlings may still be produced. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;"> 11, 12 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;">This has been attributed mainly to the absence of suitable ecological conditions for fertilisation or germination of seedlings. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">11, 12 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> The seeds are denser than water, hence they sink to the bottom or get caught in the dense mat of plants. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">12 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;">The floating mat of water hyacinth plants blocks sunlight from reaching the seeds in such conditions, preventing germination of seeds. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">12 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Asexual reproduction of water hyacinth occurs through stolons which form daughter plants. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">2, 3 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> The stolons of water hyacinth have several nodes, and each node can produce a new daughter plant which can in turn produce more stolons. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">2, 3 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> In the Nile river system, an adult plant can produce an average of 43 new daughter plants in 50 days. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">13

=**__<span style="font-family: 'Times New Roman',Times,serif; font-size: 14pt;">Impacts of Water Hyacinth Invasions __**=

<span style="font-family: 'Times New Roman',Times,serif; font-size: 12pt;"> <span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Water hyacinth is listed by law as a noxious weed in a number of countries. It is the most widespread and damaging aquatic plant species in Africa; it is estimated that the economic impacts of the weed in Africa alone may be as much as US$100 million annually. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">4, 14 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Outside of its native range in South America, the water hyacinth has few natural enemies and can proliferate extremely rapidly. 4 <span style="font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 1.5;">At the peak of the infestation of Lake Victoria, the second largest freshwater lake in the world, it was estimated that the water hyacinth mat was growing at 3 hectares (roughly 24 Olympic sized swimming pools) per day. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; line-height: 1.5; vertical-align: super;">15 <span style="font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 1.5;"> The water hyacinth is also prevalent in the Mekong delta in Vietnam, Cambodia, Lao PDR and Thailand. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">16 <span style="font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 1.5;"> In Thailand and Vietnam, biological control methods and various legislations have been put in place to control the spread of water hyacinth, but the weed remains a problem in the region. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">16 <span style="font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 1.5;"> The socioeconomic impacts of water hyacinth invasions depend on the severity of the invasion. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; line-height: 1.5; vertical-align: super;">10

**<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Biodiversity **
<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Due to its rapid rate of growth and reproduction, this weed can out-compete other aquatic plants. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">2, 3, 4, 10, 16 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;">The large dense floating mats of water hyacinth block sunlight and monopolise nutrients, killing submerged aquatic plants. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">4, 10 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> The mats not only block sunlight, preventing phytoplankton and submerged plants from photosynthesising, they also prevent oxygen from dissolving into the water, thus causing an overall drop in dissolved oxygen concentrations. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">4, 10 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Aquatic organisms sensitive to changes in dissolved oxygen levels will be negatively affected. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">4, 10 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;">However, the complex root systems and leaves of water hyacinth mats may also provide refuge for aquatic organisms, especially epiphytic invertebrates like snails and aquatic insects. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">10 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Fish population compositions can also be affected. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">10 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;">In some areas, fish populations have even increased due to the water hyacinth. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">10 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;">The overall effect of water hyacinth invasions on biodiversity is dependent on many factors. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">10 <span style="font-family: 'Times New Roman',Times,serif; font-size: 12pt;">The diagram below shows interactions between water hyacinth and other components of a freshwater community. The introduction of water hyacinth has can affect a freshwater ecosystem through its interactions with all these parts of the ecosystem, which interact with each other as well, making it difficult to predict the exact ecological effects of an invasion.



**<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Pests and Vectors **
<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Water hyacinth mats have the effect of slowing water flow, creating suitable breeding grounds for mosquitoes that carry diseases such as malaria and human lymphatic filariasis, and snails which are vectors for schistosomiasis. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">4 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> Incidence of cholera was also found to be positively correlated with water hyacinth cover in Nyanza Province in Kenya that borders Lake Victoria. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">4 ==**<span style="font-family: 'Times New Roman',Times,serif; font-size: 12pt;">Socio-economic Impacts **== <span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Water hyacinth mainly impacts the economy by clogging waterways, disrupting ship and boat navigation and restricting access to water for recreation, fisheries, and tourism. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">4, 10 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;">In Kenya, water hyacinth mats rendered fishing grounds in Lake Victoria inaccessible, decreasing fish catch rates by 45%. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">4 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> In parts of Nigeria and Cameroon, entire waterways have been rendered impassable due to this weed. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;"> 4, 10 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;">In parts of India, water hyacinth blockages in irrigation channels reduce irrigation for crops and even cause flooding. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">17 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> The plants can also get caught in hydropower dams: clearing water hyacinth from the hydroelectric dam at the Owen Falls in Uganda costs about US$1 million per year. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">4, 18 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Management of water hyacinth is also costly. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">10 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;">See control methods.

**<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Water Quality **
<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Water hyacinth invasions will cause a decrease in dissolved oxygen, but they are also able to absorb contaminants, heavy metals and excessive nutrients from the water column. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">10 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> See phytoremediation.

=__**<span style="font-family: 'Times New Roman',Times,serif; font-size: 14pt;">Water Hyacinth in Singapore **__=

<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">The water hyacinth was introduced into Singapore by a resident in 1893 from Hong Kong for cultivation in his private garden. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">19 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> From there, it was introduced to the Singapore Botanic Gardens. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">19 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> Chinese farmers living the area probably took it from there to grow as feed for ducks and pigs. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">19, 20 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> Initially, the water hyacinth did not pose problems, most likely because it was confined to fish ponds and was removed regularly for feeding livestock. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">19, 20 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Water hyacinth only became a problem in Singapore after the damming of the Kranji River to build the Kranji Reservoir. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">19 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;">The dam trapped wastes washed in from pig, poultry, vegetable and fish farms in the catchment area in the reservoir. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">19 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> Water hyacinth thrived in the nutrient rich waters of the reservoir, prompting the Public Utilities Board (PUB) to take action. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">19 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> Being a reservoir for drinking water, chemical management using herbicides was out of the question. Tug boats and machinery were employed to physically remove the plants. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">19, 21 <span style="font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 1.5;"> This proved only partially effective, because the removed plants were left on the banks of the reservoir, returning nutrients back into the water when the dead plants rotted. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">19

<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">At the same time, pig farming was banned in water catchment areas and relocated to an intensive pig farming estate in Punggol. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">19, 22 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> By 1977, relocation of pig farms located within the catchment of the Kranji Reservoir was completed. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">19 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> This helped to relieve the situation by reducing nutrient input into the reservoir. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">19

<span style="font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 1.5;">Even now, water hyacinth still poses a problem in the Kranji Bund Marshes along the western shore of the Kranji Reservoir. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; line-height: 1.5; vertical-align: super;">23 <span style="font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 1.5;"> The Nature Society of Singapore (NSS) adopted the Kranji Bund Marshes under the Active, Beautiful and Clean Waters Program adoption scheme in 2008. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; line-height: 1.5; vertical-align: super;">24 <span style="font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 1.5;"> Part of their pond maintenance program is to clear aquatic weeds that clog the marshes, such as water hyacinth, in order to restore the open water habitat for water birds. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; line-height: 1.5; vertical-align: super;">24, 25 <span style="font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 1.5;"> Water hyacinth is also known to speed up the rate of evapotranspiration, which could be contributing to the drying up of the Kranji Bund Marshes. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">4, 10

=__**<span style="font-family: 'Times New Roman',Times,serif; font-size: 14pt; line-height: 1.5;">Control Methods **__=

<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">There are a variety of methods employed to manage water hyacinth invasions. Usually, a number of the following methods are used in conjunction with each other. For maximum effectiveness, management programs should also involve the local community and other stakeholders to target root causes (eg high nutrient loads due to pollution). <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">4 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> There have been no instances of successful eradication of water hyacinth from an area once it is established. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">26 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;">The control methods described below only cover methods to manage an already existing water hyacinth infestation. Prevention measures such as quarantine are not described.

**<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Physical Control **
<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Physical control methods usually involve dredging or cutting up the weeds. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">27 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> This can be done manually, or with machines such as aquatic weed harvesters, tugboats or vegetative cutters. Manual physical control is slow and laborious, and therefore expensive, especially in countries with high labour costs. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;"> 27 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> To maximize effectiveness, the plants have to be removed from the water and disposed of elsewhere to prevent the recycling of nutrients back into the water, as was the case in Kranji Reservoir in Singapore. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">19 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> Also, the cut up plant parts may still produce clones. Rotting masses of water hyacinth could also pose a problem for water quality. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">28 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> Moreover, the rate of physical removal needs to be able to keep up with the rate of regeneration. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;"> 29 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> Physical removal is the main management method employed in China, but it has been rather ineffective as the weeds were regenerating faster than they were being removed. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">29 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;">There are other types of physical control which involve manipulation of the environment to prevent growth of aquatic weeds. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">27, 28 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;">For example, the drawdown method involves removing water from water bodies until a desired depth that will inhibit growth of water hyacinth. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">28 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;">This method has been found to be effective on water hyacinth infestations, but destroys the ecosystem and interferes with use of water bodies. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">28 media type="youtube" key="Xqq5l6ODSHc" width="492" height="371" align="center"

**<span style="font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 1.5;">Chemical Control **
<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Herbicides can also be used to control water hyacinth populations. Due to fears of pollution of water bodies, chemicals that can be sprayed are regulated stringently in most places. In the US, there are only 6 herbicides that are registered with and approved by the Environment Protection Agency for use in water. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">28 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> The registration process of aquatic herbicides is costly and lengthy, taking up to U$20–40 million and 8–12 years due to extensive testing to ensure safety and determine guidelines for safe usage. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">28 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> Herbicides do not act on the plants immediately. This means that effective chemical management of water hyacinth will need to consider not only the rate at which the herbicide acts on the plant, but also other environmental factors that determine the duration the herbicide stays in the water. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">28

**<span style="font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 1.5;">Biological Control **
<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">This method is based on the premise that invasive species are able to establish themselves so well in new environments because of the lack of natural predators. Natural predators from the native land are then introduced into the new system to control populations of the invasive species. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">28 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> Biological control alone is unlikely to be able to eradicate the water hyacinth, only reduce infestations to less problematic levels. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;"> 4 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> If the species introduced is not selected carefully, biological control methods may do more harm to the environment. See <span style="font-family: 'Times New Roman',Times,serif; font-size: 12pt;"> Indian mongoose introduction to control habu snake in Japan. <span style="font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 1.5;">Two water hyacinth weevils ( //<span style="font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 1.5;">Neochetina eichhorniae //<span style="font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 1.5;"> and //<span style="font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 1.5;">Neochetina bruchi //<span style="font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 1.5;">) and two water hyacinth moths ( //<span style="font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 1.5;">Niphograpta albiguttalis //<span style="font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 1.5;"> and //<span style="font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 1.5;">Xubida infusella //<span style="font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 1.5;">) have been introduced as biological control agents in a number of countries. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; line-height: 1.5; vertical-align: super;"> 4, 28 <span style="font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 1.5;"> These insects were found to be host specific to water hyacinth, and can decrease plant mass and slow proliferation to some degree. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; line-height: 1.5; vertical-align: super;">30 <span style="font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 1.5;"> After the initial costs of breeding and introduction, once a certain threshold has been reached, this control method is self-sustaining. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; line-height: 1.5; vertical-align: super;">30

**<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Utilisation Control **
<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Control by using the water hyacinth is not a specific control method, but an additional benefit from controlling water hyacinth invasions. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">4, 26 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;">See uses.

=**__<span style="font-family: 'Times New Roman',Times,serif; font-size: 14pt; line-height: 1.5;">Uses __**=

**<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Bioenergy Production **
<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Water hyacinth is almost ideal for bioenergy production – it is an abundantly available perennial non-crop plant with high cellulose content and grows rapidly. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">4 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> However, its high water content of over 90% is a disadvantage because it complicates harvesting and processing. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">4 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> In order for water hyacinth to become commercially viable for bioenergy production, the technical difficulties and low yield caused by high water content need to be overcome first. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">4, 31 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> Due to the expertise and specialized machinery required, it is not a practical source of alternative fuel for local communities. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">31

**<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Phytoremediation **
<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Water hyacinth has attracted considerable attention because of its ability to grow in heavily polluted water and absorb contaminants, heavy metals and excessive nutrients from the water column. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">10, 31 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> For example, it is known to accumulate toxic metals such as lead, copper, zinc and aluminium, and organic pollutants such as phenolic compounds. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">31 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> Moreover, water hyacinth has a high affinity for certain pollutants, and is able to accumulate them in its tissues even if they are present in trace concentrations in the water. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt;">31 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> As such, water hyacinth has potential for phytoremediation in polluted and eutrophic waters, which could be cheaper than modern wastewater treatment techniques. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">10 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> Studies have found that it is effective in treating domestic wastewater, agricultural runoff, livestock wastes and industrial effluent. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">31 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> It has been used for removing inorganic nutrients, toxic metals and even persistent organic pollutants. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">31 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> However, the benefits of phytoremediation have to be weighed against the possible problems that introduction of water hyacinth may bring about. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">10

**<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Others **
<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Fibers from water hyacinth stems can be used to make rope, baskets, fashion acessories and paper. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">31 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> Several small-scale cottage industry papermaking projects have been successful in Philippines, Indonesia, and India. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">31 media type="youtube" key="3afcYshXilM" width="444" height="271" align="left"

<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">There is even a social enterprise dedicated to making sanitary pads from water hyacinth fibers. The project aims to improve feminine sanitation for women in Africa who are unable to afford sanitary pads, while dealing with the water hyacinth problem at the same time. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">32 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> See JaniPad for more information.



=__**<span style="font-family: 'Times New Roman',Times,serif; font-size: 14pt; line-height: 1.5;">Taxonomy **__= <span style="font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 1.5;">Vernacular name: (Common) water hyacinth

<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Scientific name: //<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Eichhornia crassipes //<span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> (Mart.) Solms, 1883

<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Synonyms: //Pontederia crassipes// Mart., //Pontederia elongata// Balf., //Pontederia crassicaulis// Schltdl., //Eichhornia cordifolia// Gand., //Eichhornia crassicaulis// Schltdl., //Eichhornia speciosa// Kunth [illegitimate], //Heteranthera formosa// Miq., //Piaropus mesomelas// Raf., //Piaropus crassipes// (Mart.) Raf., //Pontederia crassipes// Roem. & Schult. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">33 <span style="font-family: 'Times New Roman',serif; font-size: 12pt;">History: Water hyacinth was first described by Carl Friedrich Philipp von Martius (1794 – 1868), a German botanist and explorer, in 1823 under the name //Pontederia crassipes.// It was subsequently moved to the genus //<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Eichhornia //<span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> by Hermann Maximilian Carl Ludwig Friedrich zu Solms-Laubach (1842 - 1915), a German botanist, in 1883.

<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Type: <span style="font-family: 'Times New Roman',Times,serif; font-size: 12pt;">Lectotypified by C. N. Horn, 1994. Pontederiaceae in Görts-van Rijn (Ed.), Flora of the Guianas, Series A: Phanerogams. Fascicle 15: 94. 1994. Supposedly located in Bahia, Brazil, Rio San Francisco near Malhada. More specific information unavailable.

=__**<span style="font-family: 'Times New Roman',Times,serif; font-size: 14pt;">Phylogeny **__=

<span style="font-family: 'Times New Roman',Times,serif; font-size: 12pt;">The following tree presents phylogenetic relationships between monocotyledons. The family Pontederiaceae, which water hyacinth is a part of, is highlighted by the red box in the diagram. <span style="font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 1.5;">The tree was constructed using matK (maturase K gene) and rbcL sequences from 113 genera of 45 families. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; line-height: 1.5; vertical-align: super;">34 <span style="font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 1.5;">The chloroplast gene matK and protein encoding gene rbcL are two of the genes that have been proposed to be used in DNA barcoding for plants. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; line-height: 1.5; vertical-align: super;">34, 35

<span style="font-family: 'Times New Roman',Times,serif; font-size: 12pt;">The multiple studies have been done on the phylogeny of the family Pontederiaceae using different genes. There does not appear to be much consensus in the results of the different studies. The following trees show tree shows water hyacinth's position in the family Pontederiaceae. For more information on the trees, see original article for the tree on the left, and see [|original article] for the tree on the right. <span style="font-family: 'Times New Roman',Times,serif; font-size: 8pt; vertical-align: super;">36, 37 <span style="font-family: 'Times New Roman',Times,serif; font-size: 12pt;"> Please note that the trees do not include all species in the family Pontederiaceae.


 * __<span style="font-family: 'Times New Roman',Times,serif; font-size: 14pt; line-height: 1.5;">References __**

<span style="font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 1.5;">[1] <span style="font-family: 'Times New Roman',serif; font-size: 12pt;">“Species information: //Eichhornia crassipes//” by Hyde, M.A., Wursten, B.T., Ballings, P. & Coates Palgrave, M. Flora of Zimbabwe, 2014. URL: [] (accessed 21 November 2014).

<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">[2] Gopal B. 1987. Water hyacinth. Amsterdam: Elsevier Science Publishers.

<span style="font-family: 'Times New Roman',Times,serif; font-size: 12pt;">[3] <span style="font-family: 'Times New Roman',serif; font-size: 12pt;">“//Eichhornia crassipes// (aquatic plant)”, by Invasive Species Specialist Group [ISSG]. Global Invasive Species Database, 04 Aug 2006. URL: [] (accessed 10 Oct 2014).

<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">[4] United National Environment Programme (UNEP), 2013. Water hyacinth: Can its aggressive invasion be controlled? URL: [] (accessed 5 Nov 2014).

<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">[5] Téllez, T., López, E., Granado, G., Pérez, E., López, R. & Guzmán, J., 2008. The water hyacinth, //Eichhornia crassipes//: an invasive plant in the Guadiana River Basin (Spain). //Aquatic Invasions// //3//(1): 42-53.

<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">[6] Ministry for Primary Industries, 2013. Water hyacinth. URL: <span style="font-family: 'Times New Roman',Times,serif; font-size: 12pt;">[] (accessed 11 Nov 2014).

<span style="font-family: 'Times New Roman',Times,serif; font-size: 12pt;">[7] Australian Weeds Committee, 2012. Water hyacinth: National strategy 2012 to 2017. URL: <span style="font-family: 'Times New Roman',Times,serif; font-size: 12pt;">[] (accessed 11 Nov 2014).

<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">[8] “Water hyacinth (//Eichhornia crassipes//)”, by NSW Department of Primary Industries, Mar 2010. Department of Primary Industries. URL: [] (accessed 5 Nov 2014).

<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">[9] “//Eichhornia crassipes//”, by Missouri Botanical Garden, n.d. Missouri Botanical Garden. URL: [] (accessed 5 Nov 2014)

<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">[10] Villamagna, A. M. & Murphy, B. R., 2010. Ecological and socio-economic impacts of invasive water hyacinth (//Eichhornia crassipes//): A review. //Freshwater Biology, 55//(2): 282–298.

<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">[11] <span style="font-family: 'Times New Roman',Times,serif; font-size: 12pt;">Barrett S.C.H. 1980. Sexual reproduction in //Eichhornia crassipes// (water hyacinth). 1. Fertility of clones from diverse regions. //Journal of Applied Ecology 17//(1):101-112.

<span style="font-family: 'Times New Roman',Times,serif; font-size: 12pt;">[12] Barrett S.C.H. 1980. Sexual reproduction in //Eichhornia crassipes// (water hyacinth). II. Seed production in natural populations. //Journal of Applied Ecology 17//(1):113-124.

<span style="font-family: 'Times New Roman',Times,serif; font-size: 12pt;">[13] Batanouny, K. H. & El-Fiky, A. M., 1975. The water hyacinth (//Eichhyornia crassipes// solms) in the Nile system, Egypt. //Aquatic Botany, 1//: 243–252

<span style="font-family: 'Times New Roman',Times,serif; font-size: 12pt;">[14] United Nations Environmental Program [UNEP], 2006. Africa environment outlook 2: Our environment, our wealth. URL: <span style="font-family: 'Times New Roman',Times,serif; font-size: 12pt;">[] (accessed 12 Nov, 2014).

<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">[15] Ayodo, T. & Jagero, N., 2012. The economic, educational and social responsibilities of elders development groups in Lake Victoria region. //Academic Research International, 2// (3): 610-620.

<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">[16] MWBP/RSCP, 2006. Invasive alien s <span style="font-family: 'Times New Roman',Times,serif; font-size: 12pt;">pecies in the Lower Mekong Basin: Current state of play. Mekong Wetland Biodiversity Programme and Regional Species Conservation Programme, The World Conservation Union (IUCN). URL: [] (accesed 12 Nov 2014).

<span style="font-family: 'Times New Roman',Times,serif; font-size: 12pt;">[17] <span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Patel, S., 2012. Threats, management and envisaged utilizations of aquatic weed //Eichhornia crassipes//: An overview. //Reviews in Environmental Science and Bio/Technology, 11//: 249–259.

<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">[18] Mailu, A., 2001. Preliminary assessment of the social, economic and environmental impacts of water hyacinth in the Lake Victoria basin and the status of control. In: Biological and integrated control of water hyacinth, //Eichhornia crassipes//. ACIAR Proceedings No. 102.

<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">[19] Wee, Y. C. & Corlett, R., 1986. The city and the forest: Plant life in urban Singapore. Singapore: Singapore University Press.

<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">[20] "The 'aliens' in Singapore”, by Lim, K. S. Nature Watch, Sep 1998. URL: <span style="color: #000000; font-family: 'Times New Roman',serif; font-size: 12pt;">[] <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> (accessed on 29 Oct 2014).

<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">[21] Public Utilities Board [PUB], 2013. PUB annual report 2012/ 2013: Commemorating 50 years of water from the first drop. URL: <span style="font-family: 'Times New Roman',serif; font-size: 12pt;">[] (accessed on 29 Oct 2014).

<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">[22] "History: Our past - The Primary Production Department”, by Agri-Food & Veterinary Authority (AVA). Agri-Food & Veterinary Authority of Singapore, 17 Jan 2014. URL: <span style="color: #000000; font-family: 'Times New Roman',serif; font-size: 12pt;">[] <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> (accessed 1 Nov 2014).

<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">[23] "Kranji bund marshes”, by Ho, H. C. Nature Watch, Apr 2002. URL: <span style="color: #000000; font-family: 'Times New Roman',serif; font-size: 12pt;">[] <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> (accessed 1 Nov 2014).

<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">[24] "NSS Kranji Reservoir Adoption Program and Ceremony”, by Jain, A. Nature Society of Singapore, 29 Nov 2008. URL: <span style="color: #000000; font-family: 'Times New Roman',serif; font-size: 12pt;">[] <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> (accessed 1 Nov 2014).

<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">[25] “Pond restoration - The heroes at work”, by Jain, A. Nature Society of Singapore, 27 Sep 2009. URL: [] (accessed 1 Nov 2014).

<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">[26] European Environment Agency, 2012. The impacts of invasive alien species in Europe. URL: [] (accessed 16 Nov 2014).

<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">[27] Murphy, K. J., 1988. Aquatic weed problems and their management: A review. II. Physical control measures. //Crop Protection, 7//: 283-302.

<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">[28] Madsen, J. D., 1997. Methods for management of nonindigenous aquatic plants. In Luken, J. O. & Thieret, W. T. (Eds.), Assessment and management of plant invasions (pp. 145-170). New York: Springer Science & Business Media.

<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">[29] Lu, J., Wu, J. & Zhu, L. 2007. Water hyacinth in China: A sustainability science-based management framework. //Environmental Management, 40//:823–830.

<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">[30] Ochiel, G. R. S. & Stephen W Njoka, S. W., 2012. Biological control and monitoring of water hyacinth, //Eichhornia crassipes//, Marts. Solms-Laubach (Liliales: Ponteridiaceae) during the post-resurgence period in Lake Victoria basin, Kenya. URL: [] (accessed 16 Nov 2014).

<span style="font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 1.5;">[31] Malik, A., 2007. Environmental challenge vis a vis opportunity: The case of water hyacinth. //Environment International 33//(1):122–138.

<span style="font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 1.5;">[32] Lidman, K., Thornander, S., Hoogendijk, M., Vedeler, L. M. & Tobiassen K. 2009. New sense in nuisance. URL [] (accessed 12 Nov 2014).

<span style="font-family: 'Times New Roman',serif; font-size: 12pt; line-height: 1.5;">[33] <span style="font-family: 'Times New Roman',serif; font-size: 12pt;">“ //<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Eichhornia crassipes //<span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> (Mart.) Solms”, by The Plant List. The Plant List, 2010. URL: [] (accessed 5 Nov 2014).

<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">[34] Tamura, M. N, Yamashita, J., Fuse, S. & Haraguchi, M., 2004. Molecular phylogeny of monocotyledons inferred from combined analysis of plastid matK and rbcL gene sequences. //Journal of Plant Research, 117//:109–120.

<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">[35] Yu, J., Xue, J. H., & Zhou, S. L. 2011. New universal matK primers for DNA barcoding angiosperms. //Journal of Systematics and Evolution, 49//(3): 176–181.

<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">[36] Ness R. W., Graham, S. W. & Barrett, S. C. H., 2011. Reconciling gene and genome duplication events: Using multiple nuclear gene families to infer the phylogeny of the aquatic plant family Pontederiaceae. //Molecular Biology and Evolution, 28//(11): 3009–3018.

<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">[37] Graham, S. W., Olmstead, R. G. & Barrett, S. C. H., 2002. Rooting phylogenetic trees with distant outgroups: A case study from the Commelinoid Monocots. //Molecular Biology and Evolution, 19//(10): 1769–1781.