Ipomoea aquatica

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. ==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. Several sources have also cited China or India as the location of the plant's domestication. 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 ==

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 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. 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. 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. == 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. File:Adobong kangkong (Philippines).jpg|Filipino adobong kangkóng File:Ensaladang kangkong.jpg|Filipino ensaladang kangkóng File:Pelecing kangkung.JPG| Indonesian plecing kangkung from Lombok File:Mie Kangkung.JPG|Indonesian mie kangkung (with noodles) File:Gendar Petis Kangkung.jpg|Indonesian petis kangkung (with gendar rice cake) from Semarang File:Kangkungblacan.jpg|Malaysian-style kangkung belacan File:Pak boong fai daeng.jpg|Thai phak bung fai daeng File:Canhchua2.jpg|Vietnamese canh chua File:HK 上環市政大廈 Sheung Wan Municipal Building Cooked food centre 棟記 Tung Kee Restaurant dinner food August 2019 SSG 10.jpg|Hongkong-style kōngxīncài File:Food 炒牛肝, 小吳現炒牛肉, 天母, 台北 (15256971207).jpg|Taiwanese-style kōngxīncài 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. 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. In limited quantities, I. aquatica can have a somewhat laxative effect. 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==

, Philippines , Philippines 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: • 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. It is also found in Africa and in its wild form; it is collected and used by the Sambaa people in Tanzania. Water spinach is also potentially suitable for cultivation in greenhouses in more temperate regions. The wetland method is the traditionally more common and important method for cultivation in Hong Kong: In the wetland method, water spinach is cultivated on flat fields surrounded by raised banks, which have oftentimes been used as rice paddies in the past. These former rice paddies have a heavy clay soil with an iron-pan. This helps to retain water for the water spinach. The seedlings to be used in this method are usually grown in a nursery on a dry field, as germination under water is quite poor. Six weeks after sowing, cuttings can be taken from the seedlings for transplantation. One cutting is an approximately long cut from the stem containing seven or eight nodes. This is then planted in the field with a spacing of about . The field is prepared beforehand by flooding it to a depth of . The soil itself is tramped into a liquid mud so that the cuttings can root easily. Once the plants are established, the depth of the flooding is increased to . The first harvest in the wetland method can usually be done at around 30 days after transplantation. Also, the harvesting differs from the dryland system: In the wetland, the upper part of the main shoot is cut at about water level. This stimulates lateral growth and produces horizontal shoots carrying vertical branches. After the first harvests, every seven to ten days throughout the summer, these vertical branches can be harvested. After the planting period, the fields are drained and once the fruit of the water spinach is ripe, it is harvested, dried, then trodden to release the seeds which are to be used for the following season. A specialist pathogen on I. aquatica is the oomycete Albugo ipomoeae-aquaticae, though its range is restricted to southern and southeast Asia. especially in the states of Florida, California, and Hawaii, where it can be observed growing in the wild. In the US, water spinach has mainly become a problem in Florida. It is unclear why it is a problem there; however, although the fast growth rate has been cited as a threat to native plants in certain areas of Florida. It could be owing to the time since introduction, or owing to climatic factors. Possession of I. aquatica has been prohibited in Florida since 1973, but it is still being grown and sold illegally. Some of the infestations in Florida public lakes have been eradicated, or at least attempts have been made. In Sri Lanka it invades wetlands, where its long, floating stems form dense mats which can block the flow of water and prevent the passage of boats. ==Gallery==

File:04657jfDampol Rueda Plaridel Pungo Calumpit Bulacan Riverbanks Kangkung Viaductfvf 26.jpg|I. aquatica along the Angat River, Philippines File:Starr-121029-0421-Ipomoea aquatica-habit in wetland-Ukumehame-Maui (24827090269).jpg|Ipomoea aquatica in Ukumehame, Maui, Hawaii File:Immature seeds of Ipomoea aquatica 2.jpg|Immature fruits of Ipomoea aquatica File:Ipomoea aquatica Nksw 4.jpg|Ipomoea aquatica at Nakhonsawan school, Nakhon Sawan, Thailand File:Ipomoea aquatica bd-3.jpg|Fruits of Ipomoea aquatica File:Ipomoea aquatica (Marsh Glory) flower W IMG 0403.jpg|Close-up of I. aquatica flower in Hyderabad, India File:9916Wawa Poblacion Balagtas 13.jpg|Freshly-harvested I. aquatica bundles being unloaded from rafts in the Philippines File:甕菜 Ipomoea aquatica -香港西貢獅子會自然教育中心 Saikung, Hong Kong- (9240155912).jpg|I. aquatica with white flowers in Sai Kung, Hong Kong File:Bubulcus ibis in the Philippines 22.jpg|Cattle egrets among I. aquatica in Norzagaray, Philippines File:HK WCD 灣仔 Wan Chai 春園街 Spring Garden Lane shop Kai Bo Food Supermarket vegetable July 2021 SS2.jpg|I. aquatica being sold in a market in Hong Kong File:Ipomoea aquatica.jpg|I. aquatica bundles sold in a market in Sarawak, Malaysia File:03899jfPasig City Boundary Buting Bridge School Creek Monument Makati Cityfvf 19.jpg|Bundles of I. aquatica being sold by a roadside vendor in Makati City, Philippines ==See also==