APA Sample Invasive Species

Running head: INVASIVE SPECIES 1

Invasive Species

Name

Institutional Affiliation

INVASIVE SPECIES 2

Invasive Species

Name: Water hyacinth

Species: Eichhornia crassipes

Section: Frewshater

Eichhornia crassipes is a common freshwater weed that originates from South America

and is known across the world. The plant has been regarded as one of the most troublesome

aquatic invasive species. Eichhornia crassipes was used as an ornamental plant in water due to

its attractive flowers. However, whenever it was planted in an appropriate environment, it thrived

and spread faster to become the dominant species in the lakes, rivers, and other water bodies.

Such a phenomenal monotypic stand negatively affected human activities and biodiversity in

those water bodies. Besides, approaches to eradicate the plant have been quite challenging and

useless considering the agents of dispersal and growth rate that makes Eichhornia crassipes

survive (Wright, 2011). Nevertheless, the use of biological controls through an integrated

management strategy would assist in providing long-term solutions to the non-native invasive

plant.

Eichhornia crassipes is a floating plant of sub-tropical and tropical freshwaters enriched

with nutrients. At initial phases of growth, its leaves are strap-like and elongated; but they

become spathulate with swollen petioles at the developing one. However, the sizes of the plant

vary depending on the environment and the numbers of the neighbors: when there are a lot of

them, the plants tend to be taller and more erected; but while in spaced regions, they are short

due to the spreading and swelling of the petioles. The length of the shoot and the root depends on

the nutrient conditions. The striking flowers of the invasive plant consist of six stamens and a

INVASIVE SPECIES 3

single style that forms a floral trimorphism. Besides, the plant is perennial and can be propagated

by seed or vegetative reproduction.

INVASIVE SPECIES 4

Eichhornia crassipes is believed to have originated from the Amazon basin in Brazil and

was naturally distributed beyond South America. The plant was first introduced to the U.S. in

1884, where it participated in the New Orleans Cotton Exposition after which it emerged to be

problematic as it spread to Florida. However, due to the nature of its fascinating flowers, several

countries, such as Australia, Japan, Egypt, India, Philippines, and China among others,

introduced it in their botanical gardens, where it was observed as a weed. In Madagascar, the

invasive species was introduced as an ornamental plant before demonstrating the problematic

features. Besides, during the early introduction of the plant in South East Asia, it was recorded in

unknown locations, where people admired its beauty and spread it further to other places, like Sri

Lanka and Hong Kong. Chinese villagers planted Eichhornia crassipes as food to feed the pigs.

Furthermore, deliberate introduction of Eichhornia crassipes in Africa was evident

strongly and led to the troublesome infestation along the Congo River, the Nile tributaries, the

Pangani River, and River Sigi. With such consideration, the plant invaded several lakes, like

Victoria, Kyoga, Naivasha, and rivers like the Niger River, the Shire, and others. However, upon

the introduction of the invasive plant in the favorable habitats, mostly the open waters,

Eichhornia crassipes has become the dominant plant in the invaded waters hindering the growth

of other plants, fishing, and water transportation (Williams, 2006). Such a move shows the

dramatic scenarios presented by the species-spread that posed a potential threat to freshwater

bodies.

INVASIVE SPECIES 5

In the twentieth century, Eichhornia crassipes has been identified as the most

troublesome aquatic plant declared as a noxious weed. In such a consideration, the growth of the

plant has been admitted illegal in most regions, like Australia and South Africa, where even

transportation of the plant's materials is prohibited. Furthermore, various mechanical and

biological strategies have been developed to assist in the destruction of the exotic weed in

monotypic environments. Nevertheless, the inadequacy of effective control mechanism has been

reported about the worst infestations of the noxious plant.

The growth of Eichhornia crassipes is considered highly rapid since it can double its

population in about two weeks or less based on biological and ecological requirements present.

For instance, the leaves are designed in a way that they are highly productive to increase the

growth rate, where the biomass can increase by 12% daily in terrestrial ecosystems. The

flowering of the aquatic plant can be induced by shortages in nutrients and is often seasonal.

More so, despite the tristylous nature of the flowers, the plant is compatible with other different

forms that makes wind pollination useful and can produce several seeds, yet some populations

have demonstrated self-incompatibility. Furthermore, seed and vegetative propagation enable the

successful spread of the species. After maturation of the capsule, seeds are released below the

water, where they can remain dominant for years or germinate immediately under aerobic

conditions and alternating temperatures. However, the seedlings get established on muddy edges

of the water body but become free-floating due to the action of the waves and rising water levels.

On the other hand, vegetative growth happens indefinitely developing large populations of

daughter plants from the stolon of the older leaves, which shows the success in spread and

invasion of the plant without undergoing sexual reproduction.

INVASIVE SPECIES 6

The optimal temperatures for growth of Eichhornia crassipes range between 25 and 30

degrees Celsius, while growth stops at temperatures above 40 or below 10 degrees. As well,

favorable nutrient levels are required for optimum growth characterized of nitrogen and

phosphorus, where eutrophic environments record the highest growth rates since it is

proportional to nitrogen concentration in the leaves. Further, the best-suited pH for Eichhornia

crassipes growth is 6-8, while extreme pH could be detrimental to cell activities. Calcium as an

element is significant determining the growth threshold, where concentrations below 5mg/l

would cease growth (Chu, Ding, & Zhuang, 2006). Besides, the plant has shown survival in low

levels of salinity, which explains the demonstration of plants in lagoons of rivers entering the sea

waters. Meanwhile, Eichhornia crassipes is associated with some other water weeds, like Azolla

filiculoides in spite of being the dominant species.

Eichhornia crassipes has natural enemies that have assisted in the control of the non-

native weed. For instance, more than a hundred insect species and pathogen are more likely to

attack this plant than any other, which has assisted in biological control. However, most of them

are restricted in some countries, and when imported, develops preferences to other plants. Such a

move has made Eichhornia crassipes quite healthy in Asia and Africa due to the reluctance of

the local organisms to invade the plants. In such a consideration, it is important that biological

control agents in South America among other potential agents be studied to help in the mitigation

of devastating effect of Eichhornia crassipes.

INVASIVE SPECIES 7

References

Chu, J., Ding, Y., & Zhuang, Q. (2006). Invasion and control of water hyacinth (Eichhornia

crassipes) in China. Journal of Zhejiang University SCIENCE B, 7(8), 623-626.

doi:10.1631/jzus.2006.b0623

Williams, A. E. (2006, November 17). Water Hyacinth. Van Nostrand's Scientific Encyclopedia.

doi:10.1002/0471743984.vse7463.pub2

Wright, R.T., & Boorse, D.F. (2011). Environmental Science: Toward a sustainable future. (11th

ed.). San Francisco, CA: Pearson Publishing, Inc.

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