Taxonomic name: Ipomoea aquatica Forsk.
Synonyms: Convolvulus repens Vahl, Ipomoea repens Roth, Ipomoea reptans Poiret, Ipomoea subdentata Miq.
Common names: akankong (Guam), aquatic morning glory (English), aseri (Chuuk), cancon (Guam), Chinese waterspinach (English), kang kong (English), kangking (Yap), kangkong (Ulithi), kangkun (Guam), kangum (Palau), kankan (Guam), kankum (Palau), kongkong (Yap), lili vai (Samoa), liseron d’eau (French), lorenzo (Nauru), luve ne tombithi (Fiji), ndrinikava (Fiji), ota karisa (Fiji), seeri (Chuuk), seri (Chuuk), swamp cabbage (English), swamp morning glory (English), te kang kong (Kiribati), ung-choi (English), wa kumala (Fiji), water bindweed (English), water spinach (English)
Organism type: vine, climber
Ipomea aquatica is rich in iron and is used traditionally to treat gastric and intestinal disorders. However, Ipomea aquatica is highly invasive, forming dense mats over the surface of water bodies, such as lakes, ponds, marshes, canals and ditches. It is also found in very moist soils, such as the muddy banks along streams. Ipomea aquatica spreads rapidly from plant fragments and its floating seeds allow effective colonisation of new areas. Aquatic herbicides, whilst generally effective, are not specific enough to be used in many sensitive areas, making eradication very difficult.
Ipomoea aquatica is a trailing vine with milky sap. Stems are hollow, up to 3m long or more, rooting at the nodes, floating in aquatic situations.” Stone (1970, in PIER, 2003) describes the leaves as being variable but commonly 5-15cm long and 2-10cm wide and oblong-lanceolate (arrowhead shaped) in shape. The flowers are described as being, showy, funnelform like morning-glory blooms, solitary or in few-flowered clusters at leaf axils; petals white to pink-lilac; the fruit as being, an oval or spherical capsule, woody at maturity, about 1cm wide, holding 1-4 grayish seeds, these often short-hairy. Two basic forms (with many cultivars of each) are recognized worldwide for this species “red,” with red-purple tinged stems and pale pink to lilac flowers; and “green,” with fully green stems and white flowers. A single plant of Chinese water spinach may grow taller than 21m and can branch profusely (Langeland K.A. & Burks K.C, 1999).
lakes, riparian zones, water courses, wetlands
Ipomoea aquatica is found in fresh water aquatic habitats (PIER, 2003). I. aquatica has been found primarily in canals and ditches but also invades lakes. It grows well in moist soil or in still to flowing waters (Langeland K.A. & Burks K.C, 1999).
I. aquatica dwells in muddy stream banks, freshwater pond and lakes, and marshes. It is confined to the tropics and subtropics zones because it is susceptible to frosts and because it does not grow well when temperatures are below 23.9 degrees Celsius. Because of its prolific growth, this species can invade moist cultivated areas, such as rice and sugar cane fields, and other areas with varying water levels (Fears, UNDATED).
Ipomoea aquatica forms dense floating mats of intertwined stems over water surfaces, shading out native submersed plants and competing with native emergents. It is considered the second greatest problem plant in the Philippines, where it tends to overgrow freshwater marginal areas. A common to serious weed in many areas in the tropics (Langeland K.A. & Burks K.C, 1999).
Masses of tangled vegetation obstruct water flow in drainage and flood control canals. They have infested lakes, ponds, and river shorelines, displacing native plants that are important for fish and wildlife. The veins of the plant create dense impenetrable canopies over small ponds and retention basins creating stagnant water conditions that are ideal breeding environments for mosquitoes (Fears, UNDATED).
Commonly used as a food plant in Asia (PIER, 2003). Popular among some recent immigrants as a common potherb from the homeland and has been studied in Florida as a vegetable crop. This is because the plant of its rich iron content (Langeland K.A. & Burks K.C, 1999). I. aquatica is relatively rich in S-methyl methionine (Vitamin U) and is used traditionally to treat gastric and intestinal disorders. Furthermore it has been found to have insulin-like properties acting as an anti-hyperglycaemic (Malalavidhane, Wickramasinghe & Jansz, 2000).
Native range: Native to central to south China (Langeland and Burks, 1999).
Known introduced range: Asia, Africa, Australia, Pacific Islands, and South America (Langeland K.A. & Burks K.C, 1999).
Introduction pathways to new locations
Agriculture: The plant is a common herb in many traditional recipes from Asia, being rich in iron and having several medicinal properties. (Fears, UNDATED; Malalavidhane, Wickramasinghe & Jansz, 2000)
Floating vegetation/debris: I. aquatica reproduces from fragments of plant and floating seeds that allow easy translocation to new areas for subsequnt colonisation (Fears, UNDATED)
Smuggling: According to Fears (UNDATED) sale and distribution of I. aquatica is prohibited in Florida. However it has been repeatedly introduced to Florida since 1973.
Local dispersal methods
Agriculture (local): The plant is a common herb in many traditional recipes from Asia, being rich in iron and having several medicinal properties. (Fears, UNDATED; Malalavidhane, Wickramasinghe & Jansz, 2000)
Water currents: Seeds and plant fragments can be carried downstream by water currents (Fears, UNDATED)
Preventative measures: Sale and distribution of I. aquatica is prohibited in Florida, however, the plant is still repeatedly introduced there.
Chemical: According to Schardt & Schmitz (1990, in Fears, UNDATED), aquatic herbicides have been used to control the plant but the results were only temporary. 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU / Diuron) provided acceptable control in dry ditches but also controlled most other adjacent plants, which is unacceptable in areas of high conservation value. 1-1'-dimethyl-4,4'-bipyridylium dichloride (paraquat) and 2,4-dichlorophenoxyacetic acid (2,4-D) have both been shown to have an impact on plant growth (Ninomiya, Oogami, Kino-Oka, Taya, 2003). However as with DCMU, paraquat is a broad spectrum herbicide and would, in many cases, likely impact surrounding vegetation to an unacceptable level. N-(phosphonomethyl)glycine (glysophate) would probably be effective but again is a broad spectrum herbicide. More research needs to be undertaken on the effectiveness of 2,4 D which is a far more selective herbicide.
Biological: It would appear that biological control has not been attempted in its non-native habitats (Williams, A.E., pers.comm., 2004).
Under good conditions, Ipomoea aquatica can produce 190,000kg fresh weight biomass per ha in 9 months. It flowers in the warm months and produces 175-245 seeds per plant during the peak season (Langeland K.A. & Burks K.C, 1999).
Reviewed by: Dr Adrian E. Williams: APEM Ltd., Manchester Science Park, Manchester, UK
Compiled by: National Biological Information Infrastructure (NBII) & IUCN/SSC Invasive Species Specialist Group (ISSG)
Last Modified: Tuesday, 29 August 2006