Invasive Alien Species Fact Sheets

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file icon Eichhornia crassipeshot!Tooltip 09/26/2016 Hits: 913
PICKEREL WEED FAMILY
Pontederiaceae
 
COMMON NAMES
English: lilac devil, Nile lily, pickerelweed, water hyacinth, water orchid
 
DESCRIPTION
Evergreen, free-floating, aquatic plant that may become anchored in shallow water; [10–20 (–100) cm high]; roots are long and feathery; runners (10 cm long) are produced across the water surface and give rise to new plants.
Leaves: Dark green, shiny, hairless, simple, oval to egg-shaped to almost rounded (2–25 cm long and 2–15 cm wide) with swollen bladder-like stems (30 cm long).
Flowers: Pale violet or blue (4–6 cm long and 3.5–5 cm wide), upper petal of each flower has a prominent yellow-centred patch; flowers in clusters of 8–10.
Fruits: Capsules (a dry fruit that opens at maturity) (10–15 mm long), containing very fine seeds.
 
ORIGIN
Brazil, French Guiana, Guyana, Suriname and Venezuela
 
REASON FOR INTRODUCTION
Ornament
 
INVADES
Irrigation channels, dams, ponds, floodplains, swamps, wetlands, lakes and slow-moving rivers.
 
IMPACTS
This aquatic weed has the ability to form thick mats which hamper water transport; inhibit or even prevent fishing-related activities; block waterways and canals; hamper hydroelectricity generation; and provide breeding sites for vectors of human and animal diseases, increasing the incidence of malaria, encephalitis, schistosomiasis, filariasis, river blindness and possibly cholera (Burton, 1960; Spira et al., 1981; Gopal, 1987; Viswam et al., 1989). The thick mats reduce light penetration into the water, causing declines in the concentrations of phytoplankton that support the zooplankton–fish food chain. Extensive mats of water hyacinth increase water loss through evapotranspiration, and impact rice production (Waterhouse, 1993). In southern Benin, an infestation of water hyacinth reduced the annual income of 200,000 people by about US $84 million (de Groote et al., 2003). Lost revenues for men were mostly fishing-related, while women experienced lost revenues in trade, primarily of food crops and fish.
 
Witt, Arne. 2017. Guide to the Naturalized and Invasive Plants of Southeast Asia. CAB International. Retrieved from http://www.cabi.org/cabebooks/ebook/20173158961 on 5 October 2018.

 

file icon Prosopis juliflorahot!Tooltip 09/27/2016 Hits: 894
PEA FAMILY
Fabaceae; subfamily: Mimosaceae
 
COMMON NAMES
English: algorroba, ironwood, mesquite
Philippines: aroma
 
DESCRIPTION
Evergreen shrub or tree with thorns/spines, multi-stemmed but occasionally single stemmed [3–5 (15) m high], twigs distinctively zigzag.
Bark: Thick, rough grey-green, scaly with age and armed with sharp thorns/spines (up to 5 cm long).
Leaves: Dark green, hairless or hairy, twice-divided, 1–3 (–4) pairs of leaf branchlets (3–11 cm long) each with 11–15 pairs of leaflets, narrow, somewhat elongated with parallel sides (6–23 mm long and 1.6–5.5 mm wide), with smooth margins, no terminal leaflet, leaves grow alternately on stem. Flowers: Yellow, small, in cylindrical spikes (5–10 cm long and 1.5 cm side), solitary or in clusters near the leaf axils, fragrant.
Fruits: Pods (several seeded dry fruits that split open at maturity), green turning yellow as they mature, flat, slightly curved (8–29 cm long and 9–17 mm wide), containing 10–20 oval seeds (2–8 mm long).
 
ORIGIN
Colombia, Costa Rica, Ecuador, El Salvador, Guatemala, Honduras, Mexico, Nicaragua, Panama and Venezuela.
 
REASON FOR INTRODUCTION
Fuelwood, timber, fodder, tannin, landscape restoration, windbreaks, shade, hedge/barrier and ornament.
 
INVADES
Roadsides, disturbed land, wastelands, fallow land, drainage ditches, woodland edges/gaps, savannah, riparian vegetation, floodplains, gullies and sandy stream beds.
 
IMPACTS
Displaces native plant species and reduces the abundance and diversity of bird and other animal species. In Ethiopia, P. juliflora has reduced understorey basal cover for perennial grasses and reduced the number of grass species from seven to two (Kebede and Coppock, 2015). By transforming habitats and eliminating pasture species, it threatens the survival of Grévy’s zebra (Equus grevyi) in invaded areas (Kebede and Coppock, 2015). Other negative impacts include encroachment onto paths, villages, homes, water sources, crop- and pasturelands; and injuries inflicted by the thorns (Maundu et al., 2009). Infestations have contributed to the abandonment of agricultural land, homes and small villages. The pollen has been identified as a major allergen (Killian and McMichael, 2004). In semi-arid parts of Africa, P. juliflora has depleted the natural resources on which thousands of people depend, spawning conflict between communities over the diminishing resources.
 
Source:
Witt, Arne. 2017. Guide to the Naturalized and Invasive Plants of Southeast Asia. CAB International. Retrieved from http://www.cabi.org/cabebooks/ebook/20173158961 on 24 October 2018
file icon Pistia stratioteshot!Tooltip 09/27/2016 Hits: 892
ARUM FAMILY
Araceae
 
COMMON NAMES
English: Nile cabbage, tropical duckweed, water cabbage, water lettuce
Cambodia: chark Thom
Indonesia: apon-apon, apu-apu, kiapu
Malaysia: kiambang
Thailand: chok, jawg
Viet Nam: bèo cái
 
DESCRIPTION
Evergreen, mat-forming, usually free-floating aquatic plant; consists of a rosette of leaves (30 cm across) with a tuft of long, feathery roots (up to 80 cm long); plants develop runners (up to 60 cm long); resemble floating lettuces.
Leaves: Pale yellow-green or greyish-green, spongy, narrow at the base and rounded at the tips (2.5–15 cm long and 2–8 cm wide), margins with a series of curved projections, leaves ribbed with 6–15 longitudinal veins radiating from the base; soft white velvety hairs are found on the top and bottom of the leaf which repel water.
Flowers: Inconspicuous, pale green or white, arising from leaf forks.
Fruits: Capsules (dry fruits that open at maturity), small, green, eggshaped or oval, (5–10 mm long).
 
ORIGIN
Brazil
 
REASON FOR INTRODUCTION
Ornament
 
INVADES
Irrigation channels, dams, ponds, floodplains, swamps, wetlands, lakes and slow-moving rivers.
 
IMPACTS
Water lettuce infestations contribute to increased rates of siltation, slowing of water flow rates, degradation of fish nesting sites, increased nutrient loading, thermal stratification, increased alkalinity, and fish and macro-invertebrate mortality (Dray and Center, 2002). Mats of water lettuce block waterways, making navigation difficult. Mats of the weed also hamper fishing activities, interfere with hydroelectricity generation and hinder flood control efforts. They provide habitats for vectors of disease, and can interfere with rice production (Holm et al., 1977; Waterhouse, 1993).
 
Source:
Witt, Arne. 2017. Guide to the Naturalized and Invasive Plants of Southeast Asia. CAB International. Retrieved from http://www.cabi.org/cabebooks/ebook/20173158961 on 24 October 2018
file icon Xanthium strumariumhot!Tooltip 10/24/2018 Hits: 685
DAISY FAMILY
Asteraceae
 
COMMON NAMES
English: large cocklebur, noogoora bur, sheep bur
Cambodia: kropeatt chrouk
Malaysia: buah anjang
Thailand: kachab
Viet Nam: cây ké dau ngua
 
DESCRIPTION
Annual, much-branched herb with erect stems (20–150 cm high) without spines; stems stout, green, brownish or reddish-brown, roughly hairy.
Leaves: Green, paler below, hairy on both surfaces, broadly eggshaped to triangular (2–8 cm long), margins irregularly toothed or lobed, on long leaf stalks (2–8 cm), held alternately on stems.
Flowers: Green, inconspicuous, in the leaf axils.
Fruits: Burrs, green turning yellowish then brown as they mature (1.5–2.5 cm long), covered with hooked spines (up to 20 mm long) and two terminal beaks.
 
ORIGIN
Uncertain, but probably Central and South America.
 
REASON FOR INTRODUCTION
Bee forage and accidentally as a contaminant.
 
INVADES
Roadsides, wasteland, disturbed land, fallow land, crops, plantations, drainage ditches, savannah, water courses, lowlands, floodplains and sandy and dry riverbeds.
 
IMPACTS
Rapidly forms large stands, displacing other plant species. X.strumarium is a major weed of row crops such as soya beans, cotton, maize and groundnuts in many parts of the world, including North America, southern Europe, the Middle East, South Africa, India and Japan (Webster and Coble, 1997). It also has a damaging impact on rice production in South-east Asia (Waterhouse, 1993). In the USA, high-density cocklebur infestations have resulted in soya bean yield losses of as much as 80% (Stoller et al., 1987; Rushing and Oliver, 1998). Infestations can also decrease soya bean seed quality and harvesting efficiency (Ellis et al., 998). Even low-density cocklebur infestations in cotton fields in the USA have contributed to seed yield losses of 60–90 kg per hectare, or approximately 5% (Snipes et al.,1982). Cocklebur has also caused yield losses in groundnuts of 31–39% and 88% at low and high densities, respectively, in the southern USA (Royal et al., 1997). X. strumarium burs lodge in animal hair and in sheep’s wool, reducing the quality and increasing treatment costs (Wapshere, 1974; Hocking and Liddle, 1986). The plants are toxic to livestock and can lead to death if eaten (Weaver and Lechowicz, 1983). Cocklebur is also an alternative host for a number of crop pests (Hocking and Liddle, 1986).
 
Source:
Witt, Arne. 2017. Guide to the Naturalized and Invasive Plants of Southeast Asia. CAB International. Retrieved from http://www.cabi.org/cabebooks/ebook/20173158961 on 24 October 2018
file icon Stachytarpheta jamaicensishot!Tooltip 10/23/2018 Hits: 620
VERBENA FAMILY
Verbenaceae
 
COMMON NAMES
English: blue porter weed, blue snake weed, Brazilian tea, Jamaica snakeweed, porterweed, snake weed
Indonesia: gewongan, jarong
Malaysia: ramput tahi babi, selaseh dandi
Philippines: albaka, bilu-bilu, bolomaros, kandi-kandilaan, limbagat, sentemiento, verbena de las antilles
Viet Nam: cây duôi chuot, hai tiên
 
DESCRIPTION
Evergreen shrubby herb (60–120 cm high), young stems green or purplish, mostly hairless and square in cross-section becoming rounded, light brown and woody as they mature; woody rootstock.
Leaves: Green with a bluish or greyish tinge, leathery, hairless or with a few hairs on veins on undersides, simple, leaves eggshaped, oval or somewhat elongated with almost parallel sides (2–12 cm long and 1–5 cm wide) with rounded tips, margins sharp but finely toothed; leaves held opposite each other on stems on stalks 5–35 mm long.
Flowers: Light blue, blue or mauve, tubular (7–11 mm long and 8 mm across) on long, curved and thick spikes (15–50 cm long and 3–7 mm thick) at the end of branches.
Fruits: Capsules (dry fruits that open at maturity), green turning dark brown, dark purple or black as they mature, small, somewhat elongated with almost parallel sides (3–7 mm longand 1.5–2 mm across).
 
ORIGIN
Belize, Brazil, Colombia, Costa Rica, Ecuador, El Salvador, French Guiana, Guatemala, Guyana, Honduras, Mexico, Nicaragua, Panama, Suriname, south-eastern USA, Venezuela, and the Caribbean.
 
REASON FOR INTRODUCTION
Medicine and ornament.
 
INVADES
Roadsides, disturbed sites, wastelands, fallow land, plantations, managed pasture, gardens, drainage ditches, savannah, forest edges/gaps, woodland edges/gaps, lowlands, floodplains and coastal environs.
 
IMPACTS
Forms dense stands outcompeting native plants for water and nutrients. Probable host of cucumber mosaic cucumovirus in India (Mathew and Balakrishnan, 1991).
 
Source:
Witt, Arne. 2017. Guide to the Naturalized and Invasive Plants of Southeast Asia. CAB International. Retrieved from http://www.cabi.org/cabebooks/ebook/20173158961 on 24 October 2018
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