Ipomoea aquatica, commonly known as water spinach or kangkung, is a semi-aquatic, tropical plant grown as a vegetable for its tender shoots. I. aquatica is generally believed to have been first domesticated in Southeast Asia. It is widely cultivated in Southeast Asia, East Asia, and South Asia. It grows abundantly near waterways and requires little to no care.
Description Ipomoea aquatica grows in water or on moist soil. Its stems are or longer, rooting at the nodes. The hollow cavity within the stem makes the plant buoyant. The leaves vary from typically sagittate (arrowhead-shaped) to lanceolate, long and broad. The flowers are trumpet-shaped, in diameter, and usually white in colour with a mauve centre. Propagation is either by planting cuttings of the stem shoots, which will root along nodes, or by planting the seeds from flowers that produce seed pods. Names Ipomoea aquatica is most widely known as kangkong (also spelled kangkung), its common name in Maritime Southeast Asia, which likely originates from either Malay or one of the languages of the Philippines. It is also known as water spinach, river spinach, water morning glory, water convolvulus, or by the more ambiguous names Chinese spinach, Chinese watercress, Chinese convolvulus or swamp cabbage. In Thailand it is called pak boong (ผักบุ้ง). It is known as () in Mandarin, () in Cantonese and in Hawaii, and () in modern Cantonese.
Origin and distribution The origin of Ipomoea aquatica is not quite clear, but it is generally believed to be native to Southeast Asia and was first cultivated there. This is supported by phylogenetic studies, its ideal climatic conditions, and the number of native pathogens in the region (like Albugo spp.); as well as its predominant cultivation range, the prevalence in usage as food and traditional medicine, and the number of distinct native names in Southeast Asian languages and language families.Li, H.-L. 1970. The origin of cultivated plants in Southeast Asia. Economic Botany 24:3-19.
Several sources have also cited China or India as the location of the plant's domestication.Chang, K-C. 1970. Beginnings of agriculture in the Far East. Antiquity 44:1-12.Westphal, E. 1993. Ipomoea aquatica Forsskal Pp. 181- 184 in Plant Resources in South-East Asia. Number 8. Vegetables. Edited by J.S. Siemonsma & K. Piluek. Pu-doc Scientific Publishers, Wageningen. However, these claims have no supporting evidence other than the appearance of the plant's name in historical records. The first clear mention of I. aquatica in Chinese records is in the Nanfang Caomu Zhuang written by the Chinese botanist Ji Han (AD 263-307). Ji Han specifically identifies I. aquatica as being "a strange vegetable of the south" with a foreign origin brought over by "western countries". The claim for an Indian origin is based on the presence of the old name for the plant in Sanskrit, presumed to be from around 200 BC, but this is putative.
Ipomoea aquatica is also found in Africa, the southwestern Pacific Islands, and northern Australia. However, in Africa and the Pacific Islands, the number of native common names isn't as varied as in Southeast Asia, and there are very few references to the local use of I. aquatica for any purpose. Similarly, in Australia, it does not have indigenous names at all and is entirely absent in the traditional diet of Indigenous Australians. These imply that I. aquatica weren't native to these regions and were likely introduced relatively late from tropical Asia.
Composition Nutrition
Safety Health risk Many of the waters where water spinach grows are fed by domestic or other waste. Pigs in southeast Asia are a natural reservoir for the intestinal parasite Fasciolopsis buski. Infections in the Mekong regions resulted from feeding on water spinach. Infections of F. buski in humans through water spinach can be anticipated. The infection can be prevented by proper preparation, such as frying or boiling.Yoshihara, S., Hung, N. P., Hung, N. H., Loc, C. B. "Helminths and Helminthiosis of Pigs in the Mekong Delta, Vietnam with Special Reference to Ascariosis and Fasciolopsis buski Infection." Jarq 33, 193-199 (1999) Contamination with thermotolerant coliforms (ThC) or protozoan parasites with fecal origin, are very likely when the water spinach is planted in wastewater fed urban systems.Vuong TA, Nguyen TT, Klank LT, Phung DC, Dalsgaard A."Faecal and protozoan parasite contamination of water spinach (Ipomoea aquatica) cultivated in urban wastewater in Phnom Penh, Cambodia." Tropical Medicine and International Health, 73-81 (2007)
Water spinach has great potential as a purifier of aquatic habitats. It is an efficient accumulator of cadmium, lead, and mercury. This characteristic can be dangerous if water spinach is planted for human or animal feed in polluted aquatic systems. Mercury in water spinach is composed mostly as methylmercury and has the highest potential of becoming a threat to human health. The edible parts of the plant have a lower heavy metal concentration. The stems and bottom of the edible portion of the plant are higher in concentration and should be removed to minimize the heavy metal intake.Gosh, S. "Wetland Macrophytes as toxic metal accumulators" International Journal of Environmental Sciences, 523-528 (2010)Göthberg A., Greger, M., Bengtsson, E. "Accumulation of heavy metals in water spinach (Ipomoea aquatica) cultivated in the Bangkok region, Thailand" Environmental Toxicology, 1934-1939 (2009)
Uses Culinary The vegetable is a common ingredient in East, South and Southeast Asian dishes, such as in stir-fried water spinach. In Singapore, Indonesia, and Malaysia, the tender shoots along with the leaves are usually stir-fried with chili pepper, garlic, ginger, dried shrimp paste (belacan/terasi) and other spices. In Penang and Ipoh, it is cooked with cuttlefish and a sweet and spicy sauce. Also known as in the Hokkien dialect, it can also be boiled with preserved cuttlefish, then rinsed and mixed with spicy paste to become . Boiled also can be served with fermented krill noodles – – and prawn mi.
In Burmese cuisine, water spinach is the primary ingredient in a Burmese salad called (), made with blanched water spinach, lime juice, fried garlic and garlic oil, roasted rice flour and dried shrimp.
In Indonesian cuisine it is called ; boiled or blanched together with other vegetables it forms the ingredient of gado-gado or pecel salads in peanut sauce. Some recipes that use include plecing kangkung from Lombok, mie kangkung (kangkong noodles) from Jakarta, and petis kangkung from Semarang.
In Thailand, where it is called (), it is eaten raw, often along with green papaya salad or nam phrik, in stir-fries and in curries such as kaeng som.
In the Philippines, where it is called , the tender shoots are cut into segments and cooked, together with the leaves, in fish and meat stews, such as sinigang. The vegetable is also commonly eaten alone. In adobong kangkóng (also called ), it is sautéed in cooking oil, onions, garlic, vinegar, and soy sauce. In (or ), it is blanched and served in vinegar or calamansi juice and fresh tomatoes and onions with salt and pepper to taste. In (or ), it is sautéed with garlic and topped with bagoong alamang (shrimp paste) or bagoong isda (fermented fish) and sliced fresh tomatoes and onions, commonly also with cubed crispy (pork belly) or pork adobo. It can also be spiced with siling haba or siling labuyo peppers, soy sauce, black pepper, and sugar. It differs from in that it does not use vinegar. A local appetiser called crispy kangkóng has the leaves coated in a flour-based batter and fried until crisp, similar to Japanese vegetable tempura.
In Chinese cuisine, Ipomoea aquatica is a popular leafy vegetable commonly stir-fried with garlic, fermented tofu, or chili, depending on regional preferences. It is particularly associated with southern China, including Guangdong and Fujian, where it is often prepared as a quick, flavorful dish. In Sichuan cuisine, it may be stir-fried with pickled chili for a spicy twist. In Taiwan, it is cooked similar to Southeast Asia, with soy sauce and dried shrimp for added umami.
Phytoremediation Using aquatic macrophytes to remove nutrients from wastewater and to control freshwater eutrophication has been reported to be a feasible way of phytoremediation. Various plants, including I. aquatica, have been tested for this use. Owing to its being edible and thus marketable, it could be an attractive option for this use.Li, M., Wu, Y. J., Yu, Z. L., Sheng, G. P., & Yu, H. Q. (2007). Nitrogen removal from eutrophic water by floating-bed-grown water spinach (Ipomoea aquatica Forsk.) with ion implantation. Water research, 41(14), 3152-3158.
Animal feed Water spinach is fed to livestock as green fodder with high nutritive value—especially the leaves, for they are a good source of carotene. It is fed to cattle, pigs, fish, ducks, and chicken.Pandey, A.K. Aquatic Vegetables. Udaipur: Agrotech Academy, 2011. Print. In limited quantities, I. aquatica can have a somewhat laxative effect.
Medicinal
I. aquatica is used in the traditional medicine of southeast Asia and in the traditional medicine of some countries in Africa. In southeast Asian medicine it is used against piles, and nosebleeds, as an anthelmintic, and to treat high blood pressure. In Ayurveda, leaf extracts are used against jaundice and nervous debility. In indigenous medicine in Sri Lanka, water spinach is supposed to have insulin-like properties.
Christophe Wiart cites several promising studies showing improvements in blood glucose levels in humans and rats and concludes that clinical trials are warranted.
Antioxidant bioactive compounds and anti-microbial substances can be detected in water spinach. Furthermore, plant extracts of water spinach inhibit cancer cell growth of Vero, Hep-2, and A-549 cells, though they have moderate anti-cancer properties.
Cultivation
Ipomoea aquatica is most commonly grown in east, south, and southeast Asia. It flourishes naturally in waterways, and requires little if any care. It is used extensively in Indonesian, Burmese, Thai, Lao, Cambodian, Malay, Vietnamese, Filipino, and Chinese cuisine, especially in rural or kampung (village) areas. The vegetable is also extremely popular in Taiwan, where it grows well. During the Japanese occupation of Singapore in World War II, the vegetable grew remarkably easily in many areas, and became a popular wartime crop.
Water spinach has been found to be cultivated in the following countries:Pinker, I., U. Bubner, and M. Böhme. "Selection of water spinach (Ipomoea aquatica Forssk.)-genotypes for protected cultivation in temperate regions." I International Conference on Indigenous Vegetables and Legumes. Prospectus for Fighting Poverty, Hunger and Malnutrition 752. 2006.
Australia Bangladesh Burma Cambodia China Fiji India Maldives Indonesia Japan Malaysia Nepal New Guinea Philippines Sri Lanka Taiwan Thailand Vietnam
In the United States, it is cultivated in California, Florida, Hawaii, Texas, Arizona, and the U.S. Virgin Islands.Chilton, Earl W. "Risk Assessment for Water Spinach (Ipomoea Aquatica) in Texas." Journal Of Aquatic Plant Management 55 (2017): 96-102. Web. It is also found in Africa and in its wild form; it is collected and used by the Sambaa people in Tanzania.Austin, Daniel F. F. "Water Spinach (Ipomoea Aquatica, Convolvulaceae) a Food Gone Wild." Ethnobotany Research and Applications 5 (2007): 123-46. Web.Vainio-Mattila, Katariina. "Wild vegetables used by the Sambaa in the Usambara Mountains, NE Tanzania." Annales Botanici Fennici. Finnish Zoological and Botanical Publishing Board, 2000.
Water spinach is also potentially suitable for cultivation in greenhouses in more temperate regions.
In non-tropical areas, it is easily grown in containers given enough water in a bright sunny location. It readily roots from cuttings.