Water hyacinth
| Water Hyacinth | |
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| Common Water Hyacinth (E. crassipes) | |
| Scientific classification | |
| Kingdom: | Plantae |
| (unranked): | Angiosperms |
| (unranked): | Monocots |
| (unranked): | Commelinids |
| Order: | Commelinales |
| Family: | Pontederiaceae |
| Genus: | Eichhornia Kunth |
| Species | |
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Seven species, including: |
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The seven species of water hyacinth comprise the genus Eichhornia.
Contents |
[edit] Description
Water hyacinth are a free-floating perennial aquatic plant native to tropical and sub-tropical South America. With broad, thick, glossy, ovate leaves, water hyacinth may rise above the surface of the water as much as 1 meter in height. The leaves are 10–20 cm across, and float above the water surface. They have long, spongy and bulbous stalks. The feathery, freely hanging roots are purple-black. An erect stalk supports a single spike of 8-15 conspicuously attractive flowers, mostly lavender to pink in colour with six petals. When not in bloom, water hyacinth may be mistaken for frog's-bit (Limnobium spongia).
One of the fastest growing plants known, water hyacinth reproduces primarily by way of runners or stolons, which eventually form daughter plants. It also produces large quantities of seeds, and these are viable up to thirty years. The common water hyacinth (Eichhornia crassipes) are vigorous growers known to double their population in two weeks.
In Assamese they are known as Meteka. In Sinhala they are known as Japan Jabara (ජපන් ජබර) due to their use in World War II to fool Japanese pilots into thinking lakes were fields usable to land their aircraft, leading to crashes. In Burmese they are known as Baydar.
In Southern Pakistan, they are the provincial flower of Sindh.
In the Philippines, they use some of the water hyacinth's stems and dry it to take its fibers and take them to form strands of string each. These pieces of string are woven or interlinked together to form a braid or cord used for making bags, footwear, wreaths, hats, vases, Christmas lanterns, and more decorative materials. Because water hyacinth are prolific to the point of being a nuisance, this lets the people earn money by selling these products for a living while cleaning up the overpopulated bodies of water that are full of water hyacinths.
[edit] Invasiveness as an exotic plant
Water hyacinth has been widely introduced in North America, Asia, Australia, Africa and New Zealand. They can be found in large water areas such as Louisiana, or in the Kerala Backwaters in India. In many areas it, particularly E. crassipes, is an important and pernicious invasive species. First introduced to North America in 1884, an estimated 50 kilograms per square metre of hyacinth once choked Florida's waterways, although the problem there has since been mitigated. When not controlled, water hyacinth will cover lakes and ponds entirely; this dramatically impacts water flow, blocks sunlight from reaching native aquatic plants, and starves the water of oxygen, often killing fish (or turtles). The plants also create a prime habitat for mosquitos, the classic vectors of disease, and a species of snail known to host a parasitic flatworm which causes schistosomiasis (snail fever). Directly blamed for starving subsistence farmers in Papua New Guinea, water hyacinth remains a major problem where effective control programs are not in place. Water hyacinth is often problematic in man-made ponds if uncontrolled, but can also provide a food source for gold fish, keep water clean and help to provide oxygen to man-made ponds.
Water hyacinth often invades bodies of water that have been impacted by human activities. For example, the plants can unbalance natural lifecycles in artificial reservoirs or in eutrophied lakes that receive large amounts of nutrients.
There are other uses being found for the abundant plants, such as for cattle food and in biogas production. Recently, they have also begun to be used in wastewater treatment due to their fast growth and ability to tolerate high levels of pollution. Parts of the plant are also used in the production of traditional handicrafts in Southeast Asia. In Bangladesh, farmers have started producing fertilizer using Water Hyacinth or Kochuripana as it is known there locally.
Eichhornia crassipes, the Common water hyacinth, has become a invasive plant species on Lake Victoria in Africa after it was introduced into the area in the 1980s.
[edit] Control
Water hyacinth can be controlled using three methods:
- Chemical Control
The application of herbicides for controlling water hyacinth has been carried out for many years and it has been found that there is a good success rate when dealing with small infestations. A main concern when using herbicides is the environmental and health related effects, especially where people collect water for drinking and washing.
- Physical Control
Physical control is performed by land based machines such as bucket cranes, draglines, or boorm or by water based machinery such as aquatic weed harvester, dredges, or vegetation shredders. Mechanical removal is seen as the best short-term solution to the proliferation of the plant. It is however costly and requires the use of both land and water vehicles.
- Biological Control
As chemical and mechanical removal is often too expensive and ineffective, researchers have turned to biological control agents to deal with water hyacinth. The effort began in the 1970s when USDA researchers released three species of weevil known to feed on water hyacinth into the United States, Neochetina bruchi, N. eichhorniae, and the water hyacinth borer Sameodes albiguttalis. Although meeting with limited success, the weevils have since been released in more than 20 other countries. However, the most effective control method remains the control of excessive nutrients and prevention of the spread of this species.
May 2010 the USDA’s Agricultural Research Service released Megamelus scutellaris as a biological control insect for the invasive waterhyacinth species. Megamelus scutellaris is a small planthopper insect native to Argentina. Researchers have been studying the effects of the biological control agent in extensive host-range studies since 2006 and concluded that the insect is highly host-specific and will not pose a threat to any other plant population other than the targeted water hyacinth. Researchers also hope that the biological control will be more resilient than existing biological controls to the herbicides that are already in place to combat the invasive water hyacinth. [2]
[edit] Industrial utilization
Since the plant has abundant nitrogen content, it can be used a substrate for biogas production and the sludge obtained from the biogas. However, due to easy accumulation of toxins, the plant is prone to get contaminated when used as feed.
[edit] Exogenous
The plant is extremely tolerant of, and has a high capacity for, the uptake of heavy metals, including Cd, Cr, Co, Ni, Pb and Hg, which could make it suitable for the biocleaning of industrial wastewater [1], [2], [3],.[4] In addition to heavy metals, Eichhornia crassipes can also remove other toxins, such as cyanide, which is environmentally beneficial in areas that have endured gold mining operations.[5]
Water hyacinth removes arsenic from arsenic contaminated drinking water. It may be a useful tool in removing arsenic from tube well water in Bangladesh.[6]
Water hyacinth is also observed to enhance nitrification in waste water treatment cells of living technology. Their root zones are superb micro-sites for bacterial communities.[7]
[edit] References
- ^ Upadhyay, Alka R.; B. D. Tripathi (2007). "Principle and Process of Biofiltration of Cd, Cr, Co, Ni & Pb from Tropical Opencast Coalmine Effluent". Water, Air, & Soil Pollution (Springer) 180 (1 - 4): 213–223. doi:10.1007/s11270-006-9264-1. http://www.springerlink.com/content/t80h067j438833j2/. Retrieved 11 November 2007.
- ^ Abou-Shanab, R. A. I. et al.; Angle, JS; Van Berkum, P (2007). "Chromate-Tolerant Bacteria for Enhanced Metal Uptake by Eichhornia Crassipes (MART.)". International Journal of Phytoremediation 9 (2): 91–105. doi:10.1080/15226510701232708. PMID 18246718.
- ^ Maine, M.A. et al.; Sune, N; Hadad, H; Sanchez, G; Bonetto, C (2006). "Nutrient and metal removal in a constructed wetland for wastewater treatment from a metallurgic industry". Ecological Engineering (Elsevier) 26 (4): 341–347. doi:10.1016/j.ecoleng.2005.12.004.
- ^ Skinner, Kathleen et al.; Wright, N; Porter-Goff, E (2007). "Mercury uptake and accumulation by four species of aquatic plants". Environmental Pollution (Elsevier) 145 (1): 234–237. doi:10.1016/j.envpol.2006.03.017. PMID 16781033.
- ^ Ebel, Mathias et al.; Evangelou, MW; Schaeffer, A (2007). "Cyanide phytoremediation by water hyacinths (Eichhornia crassipes)". Chemosphere (Elsevier) 66 (5): 816–823. doi:10.1016/j.chemosphere.2006.06.041. PMID 16870228.
- ^ Misbahuddin, M.; Fariduddin, A.T.M. (2002). “Water Hyacinth Removes Arsenic from Arsenic-Contaminated Drinking Water”. Archives of Environmental Health. 57: 516- 518.
- ^ J. Todd, B. Josephson, The design of living technologies for waste treatment / Ecological Engineering 6 (1996) 109-136
[edit] External links
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Wikimedia Commons has media related to: Water hyacinth |
- Practical uses of Water Hyacinth
- Species Profile- Water Hyacinth (Eichhornia crassipes), National Invasive Species Information Center, United States National Agricultural Library. Lists general information and resources for Water Hyacinth.
