The Beautiful Water Hyacinth: An Invasive Plant and a Biofuel
A Beautiful, Problematic, and Useful Plant
Water hyacinth is a floating plant that is admired for its beautiful pink or lavender flowers set against a background of glossy green leaves. Unfortunately, it often grows aggressively and can be very invasive. In certain areas, the plant causes major problems for people. Water hyacinth has some uses, however. One of them is its ability to act as a biofuel. When fermented on its own or in combination with animal manure, it produces a gas that can be used for cooking and other tasks.
This invasive nuisance is planta non grata in much of the world where it often jams rivers and lakes with uncounted thousands of tons of floating plant matter. A healthy acre of water hyacinths can weigh up to 200 tons.— University of Florida, Institute of Food and Agricultural Sciences
Distribution of Water Hyacinth in the Wild
Water hyacinth's scientific name is Eichhornia crassipes. It belongs to the monocot group of flowering plants. Monocots have only one cotyledon or embryonic leaf in their seeds. Dicots have two cotyledons.
The plant is native to South America. It grows in bodies of fresh water, including lakes, ponds, canals, rivers, marshes, and ditches. Water hyacinth is most abundant in slow-moving water. The plant lives in the wild in the southeastern part of the United States and is also found in California. It has been found in other parts of the United States and in a few areas in Ontario as well but hasn't become permanently established there.
Water hyacinth is sold as an ornamental plant in some parts of North America. If you're tempted to grow it in your garden or on your property, you should investigate your local laws. It may be illegal to plant it where you live because of the problems that it can cause.
Features of the Plant
Water hyacinth is a perennial plant belonging to the family Pontederiaceae, which is also known as the pickerelweed family. The plant may grow as an annual in temperate climates. Pickerelweed is an aquatic plant that is native to North America and has blue to purple flowers. A cultivated form is sold for aquatic gardens and could be an alternative for someone interested in water hyacinth.
Leaves, Petioles, and Roots
The thick and glossy leaves of water hyacinth form a rosette that floats on the water surface or extends above it. The leaves are wide and are oval or round in shape. They often have a pointed tip. Like the leaves, the petiole (leaf stem) is thick. The petiole and the nodule that it contains have a spongy texture. The interior of a nodule is shown in the photo below. The plant's roots are fibrous or feathery and are purple-black in colour. They usually hang freely in the water.
The lovely flowers are born in a spike that may be as long as twelve inches and contain as many as fifteen flowers. The stalk of the spike may be even longer than the spike itself. Each flower has six petals and is pink to lavender in colour. Technically, the petals are tepals. Although they look similar, three of them are true petals and the other three are sepals. The uppermost tepal is decorated with a splash of blue or purple that has a yellow or orange centre.
The flower contains three long and three short stamens (the male structures) and one globular stigma connected to a curved style (part of the female structure). The stigma is composed of three lobes that are tightly pressed together or are separate. The flower is pollinated by insects.
The plant reproduces quickly, which contributes to its invasiveness. The fruit is a capsule that contains many seeds. These can stay viable for many years. The plant also spreads vegetatively. Water hyacinth produces stolons (horizontal stems) that extend sideways and produce new shoots.
It might be thought that it would be easy to remove the water hyacinth from its habitat, since it isn't attached to a substrate. Unfortunately, individual plants are connected to one another and can form a dense, tangled, and heavy mat. They can also spread rapidly, covering the water.
Harmful Effects of Water Hyacinth Growth
Water hyacinth spreads rapidly and widely in a suitable environment. The mat of plant material over the surface of the water is sometimes as deep as six feet. The plant can create multiple problems.
- Water hyacinth fills the space needed by other aquatic plants and prevents their growth.
- The mat formed by the plant absorbs nutrients that other plants require.
- It also blocks the light that algae and other photosynthetic organisms in the water need in order to make food.
- The plant can harm aquatic animals, since it reduces the entry of oxygen into the water and decreases the number of algae that some of them eat.
- Dead material released from the plant mats can cause problems in the water, such as a change in pH as fungi and bacteria cause the material to decay.
Water hyacinth affects humans as well. Large growths interfere with boat travel, fishing, and swimming. They can also block drainage and irrigation channels. In addition, the water that collects on the leaves of the plants is an ideal habitat for mosquitoes, which can spread disease.
The species can be a major problem in warm climates. In cooler ones, the temperature may be warm enough for the plant to survive but too cold for it to spread rapidly, making it a bit easier to control.
Uses of the Plant
There is no doubt that the plant can cause major problems. It also has some uses, however. Some types of livestock eat water hyacinth, especially if it's prepared properly to make it more palatable for them. The plant can make a good compost due to the nutrients that it contains. In a very interesting development, researchers have discovered that it can be used as a biofuel. In addition, its stems can be dried and used in weaving.
Supporters of water hyacinth point out its beauty, its edibility for livestock, and its use in compost and as a craft material. Detractors mention its invasiveness and its ability to block waterways and interfere with human activities and health. In some places, it may be hard for people to appreciate the seriousness of the problems that the plant can cause in certain parts of the world.
Problems in Kenya Around Lake Victoria
Water hyacinth is a special problem in Kenya around Lake Victoria (and in some other areas near the lake). Many people depend on the fish obtained from the lake for their livelihood. The animals are collected and sold as food. At the moment, a large area of water is blocked by the plants, which are clogging fishing routes. As the plants spread, the ability of boats to find fish and travel through the plant mats is decreasing.
The women who rely on selling the fish from Lake Victoria have other problems in addition to decreased fish to sell. Interestingly, these problems are not caused by water hyacinth and may actually be helped by the plant in combination with technology.
The women smoke the fish caught by the fishermen. They have to walk long distances to collect enough wood to do this. An even bigger problem is that the repeated exposure to the smoke used to cook and preserve the fish is affecting the health of the women, particularly with respect to their lungs. Smoke from burning wood can be irritating for the lungs and make breathing difficult.
Air pollution caused by burning wood and charcoal is a problem for the immediate environment in another way, especially when it takes place indoors. The smoke contains chemicals called polycyclic aromatic hydrocarbons, or PAHs. Some PAHs are capable of causing cancer.
Water Hyacinth in Biogas Digesters
Scientists have discovered that the water hyacinth can a great energy source when fermented in a biodigester. Even on its own, it can provide enough energy to support a family's needs in the form of a gas that can produce a flame. When the plant is mixed with chicken manure or cow dung, the results are even better.
In 2018, the village of Dunga on the shore of Lake Victoria received two biogas digesters. The devices use a mixture of water hyacinth and cow dung to produce a gas that can be used to cook food, purify water, and incubate chicks. The material placed in the digester requires a twenty to thirty day fermentation period in order to produce the gas, which is piped to where it's needed. The plant and dung mixture is said to be clean-burning and doesn't produce smoke.
Lake Victoria is the largest lake in Africa. It's located mainly in Tanzania and Uganda but extends into Kenya. It's said to have a surface area of approximately 23,000 to 26,000 square miles, depending on the source.
Good News and a Financial Problem
The biopdigesters seem to be working well. Women are reportedly suffering from fewer illnesses and they are making more money because they don't have to spend time looking for firewood.
Around fifty additional digesters will be sent to the Kenya in the near future. They could be life-saving for many women, who usually do the cooking. The only problem with the devices is their current price of $750. This is unaffordable for most villages. Hopefully a solution to the problem will be found. Finding a source of funds or a way to reduce the price are important endeavours.
The efforts of individuals and communities can be very important in solving a water hyacinth problem. The video below describes one women's project in which dried stems of water hyacinth are used to create woven items. These items include storage baskets, bags, sandals, and other objects. The use of water hyacinth for handicrafts seems to be explanding.
Water gardeners should only use native or non-invasive plants and are encouraged to ask garden centers for plants that are not invasive.— Ontario's Invading Species Awareness Program
Dealing With a Water Hyacinth Invasion
The water hyacinth problem needs to be solved. Even when plants are beautiful, they may be undesirable outside of their native habitat and without the usual checks that keep their population under control. I can think of several plants in my part of the world where this applies, including Himalayan balsam (a pretty flowering plant), yellow flag iris, oxeye daisy, and English holly. All four are introduced plants and all are invasive and problematic in some parts of the province.
Ontario's Invading Species Awareness Program recommends several procedures for dealing with water hyacinth in North America. One of its main recommendations is to choose a different aquatic plant for a pond or water garden, as mentioned in the quote above. It also suggests that people put unwanted plants into the garbage instead of discarding them in waterways. Boats that can travel through the plants should travel slowly to reduce breaking the plant mass up and spreading sections to new areas. In addition, boats and other equipment should be washed after travelling through an area infested with water hyacinth.
Planning for the Future
Several solutions are probably needed for the water hyacinth problem, depending on where it exists and how serious it is. Clearing the plant from the water may be helpful but may have to be repeated at regular intervals. Using the gathered plants to help people is an excellent goal.
The women and men who live in areas where the plant is abundant deserve to be able to earn a livelihood safely and efficiently. Perhaps with the aid of biodigesters and the other uses of the water hyacinth they will be able to.
- Eichhornia crassipes information from the University of Florida
- Water hyacinth facts from the Montana State Government
- Information about the plant from Ontario's Invading Species Awareness Program
- Water hyacinth in California from KCET (a non-commercial and educational TV station)
- Using water hyacinth as animal feed from the Kenya Climate Innovation Center (KCIC)
- Using water hyacinth for compost from the IUCN (International Union for Conservation of Nature)
- Information about polycyclic aromatic hydrocarbons or PAHs from Tox Town (a National Institutes of Health site)
- Water hyacinth problems and use as a biofuel from The Guardian newspaper
© 2019 Linda Crampton