Ipomoea aquatica

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Ipomoea aquatica
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Asterids
Order: Solanales
Family: Convolvulaceae
Genus: Ipomoea
Species: I. aquatica
Binomial name
Ipomoea aquatica
Forssk.

Ipomoea aquatica is a semiaquatic, tropical plant grown as a vegetable for its tender shoots and leaves. It is found throughout the tropical and subtropical regions of the world, although it is not known where it originated. This plant is known in English as water spinach, river spinach,[1] water morning glory, water convolvulus, or by the more ambiguous names Chinese spinach, Chinese convolvulus, swamp cabbage or kangkong in Southeast Asia.[2] Occasionally, it has also been mistakenly called "kale" in English, although kale is a strain of mustard belonging to the species Brassica oleracea and is completely unrelated to water spinach, which is a species of morning glory. It is known as phak bung in Thai, rau muống in Vietnamese, trokuon in Khmer, kalmi shak in Bengali, kangkung in Malay and Indonesian and hayoyo in Ghana.

I. aquatica grows in water or on moist soil. Its stems are 2–3 metres (7–10 ft) or more long, rooting at the nodes, and they are hollow and can float. The leaves vary from typically sagittate (arrow head-shaped) to lanceolate, 5–15 cm (2–6 in) long and 2–8 cm (0.8–3 in) broad. The flowers are trumpet-shaped, 3–5 cm (1–2 in) in diameter, and usually white in colour with a mauve centre. Propagation is either by planting cuttings of the stem shoots that will root along nodes or planting the seeds from flowers that produce seed pods.[3][4]

Cultivation[edit]

Ong choy water spinach.

Ipomoea aquatica is most commonly grown in East and Southeast Asia. Because it flourishes naturally in waterways and requires little, if any, care, it is used extensively in 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.

In the Philippines, a variety of kangkong is grown in canals dug during the American occupation after the Spanish-American War, while another variety growing on land is called Chinese kangkong.

In non-tropical areas, it is easily grown in containers given enough water in a bright sunny location. It readily roots from cuttings.

Invasive species[edit]

I. aquatica is listed on the USDA internet site as a "Class A noxious weed",[5] especially in the states of Florida, California, and Hawaii, where it can be observed growing in the wild.[6] I. aquatica has been extensively cultivated in Texas for over 30 years, having been originally brought there by Asian immigrants. Because no evidence indicates the plant has escaped into the wild, Texas lifted its ban on cultivation for personal use with no restrictions or requirements, noting its importance as a vegetable in many cultures, and also began permitting cultivation for commercial sales with the requirement of an exotic species permit.[7] In Sri Lanka, it invades wetlands, where its long, floating stems form dense mats which can block the flow of water and prevent passage of boats.[8]

Culinary uses[edit]

Penang kangkung blachan
Thai pak boong fai daeng

The vegetable is a common ingredient in Southeast Asian dishes. 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 eng cai in the Hokkien dialect, it can also be boiled with preserved cuttlefish, then rinsed and mixed with spicy rojak paste to become jiu hu eng cai. Boiled eng cai also can be served with fermented krill noodle belacan bee hoon and prawn noodle.[9]

In the Philippines, where it is called kangkóng, the tender shoots are cut into segments and cooked, together with the leaves, in fish and meat stews, such as sinigang. The vegetable may also be eaten alone, such as in adobong kangkóng, where it is sautéed in cooking oil, onions, garlic, vinegar, soy sauce, and bouillon cube. A local appetiser called crispy kangkóng has the leaves coated in a flour-based batter and fried until crisp, similar to Japanese vegetable tempura.[10]

Chinese cuisine (Chinese: 空心菜; pinyin: kōngxīncài; literally "hollow vegetable") has numerous ways of preparation, but a simple and quick stir-fry, either plain or with minced garlic, is probably the most common. In Cantonese, the water spinach is known as 通菜 (Jyutping: tung1 coi3) or 蕹菜 (Jyutping: ung3 coi3, sometimes transliterated as ong choy). In Cantonese cuisine, a popular variation adds fermented bean curd. In Hakka cuisine, yellow bean paste is added, sometimes along with fried shallots.

In the cuisine of Cambodia, where it is called trakuon (Khmer: ត្រកួន), water spinach is known to have a few types. The popular type is the usual local water plant, used in many traditional dishes. One type is known as Chinese trakuon grown as a straight stalk plant from soil. This type is known to be used in stir fry with pork or just with marinated soy beans (sieng). The Khmer popular dish samlar machu (sour soup) uses water spinach with fish or chicken. Water spinach is also eaten raw or parboiled along with other vegetables in dip dishes, e.g. toeuk kroeung, a sour/salty taste dish, with roughly minced fish mixed with lemon juice, crushed peanuts, basil, and prahok (fish paste) flavour, similar to nam phrik.

In Thailand, where it is called phak bung (Thai: ผักบุ้ง), it is eaten raw, often along with green papaya salad or nam phrik, in stir-fries and in curries such as kaeng som.[11]

In Laos, where it is known as pak bong (ຜັກບົ້ງ), and in Burma, where it is called gazun ywet (ကန်စွန်းရွက်; MLCTS: kancwan:rwak; [ɡəzʊ́ɴ jwɛʔ]), it is frequently stir-fried with oyster sauce or yellow soybean paste, and garlic and chillies.

In Vietnam, I. aquatica (rau muống) is a common ingredient and garnish in Vietnamese cuisine and was once served as a staple vegetable of the poor. In the South, the water spinach is julienned into thin strips and eaten with many kinds of noodles. It is also commonly cooked in a sour soup (canh chua), with tomatoes, other vegetables, and some kind of protein. Rau muống is also commonly sauteed with chopped garlic, oil (or pork fat), and fish sauce, known as rau muống xào tỏi (stir-fried water spinach with garlic) and served as a side dish in many meals.

Vietnamese canh chua
Water spinach, raw
Nutritional value per 100 g (3.5 oz)
Energy 79 kJ (19 kcal)
Carbohydrates 3.14 g
- Dietary fiber 2.1 g
Fat 0.2 g
Protein 2.6 g
Vitamin A equiv. 315 μg (39%)
Thiamine (vit. B1) 0.03 mg (3%)
Riboflavin (vit. B2) 0.1 mg (8%)
Niacin (vit. B3) 0.9 mg (6%)
Pantothenic acid (B5) 0.141 mg (3%)
Vitamin B6 0.096 mg (7%)
Folate (vit. B9) 57 μg (14%)
Vitamin C 55 mg (66%)
Calcium 77 mg (8%)
Iron 1.67 mg (13%)
Magnesium 71 mg (20%)
Manganese 0.16 mg (8%)
Phosphorus 39 mg (6%)
Potassium 312 mg (7%)
Sodium 113 mg (8%)
Zinc 0.18 mg (2%)
Link to USDA Database entry
Percentages are roughly approximated
using US recommendations for adults.
Source: USDA Nutrient Database

In South India, the leaves are finely chopped and mixed with grated coconut to prepare thoran (തോരന്‍), a dish in Kerala. The same dish in Tamil Nadu is prepared as thuvaiyal (துவையல்) or as kootu (கூட்டு).

In Bangladesh and West Bengal, it is known as kolmishak (কলমীশাক) and stir-fried preparation of the leaves is a very popular dish.


Hazard[edit]

If harvested from contaminated areas, and eaten raw, I. aquatica may transmit Fasciolopsis buski, an intestinal fluke parasite of humans and pigs, causing fasciolopsiasis.[12]

Medicinal uses[edit]

Studies conducted with pregnant diabetes-induced rats have shown a blood sugar-lowering effect of Ipomoea aquatica by inhibiting the intestinal absorption of glucose.[13][14]

References[edit]

  1. ^ "Adobong Kangkong (River Spinach) Recipe". Filipinofoodrecipes.net. Retrieved 2014-01-13. 
  2. ^ "Kangkong / Ipomoea aquatica Forsk./ POTATO VINE / Herbal Medicinal Therapies / Philippine Alternative Medicine". Stuartxchange.org. Retrieved 2014-01-13. 
  3. ^ http://www.curiousgardener.com/2011/09/15/the-new-kangkong-experiment/
  4. ^ "Kangkungking.com". Kangkungking.com. Retrieved 2014-01-13. 
  5. ^ http://www.aphis.usda.gov/plant_health/plant_pest_info/weeds/downloads/weedlist.pdf "USDA Noxious Weed List"
  6. ^ http://plants.usda.gov/java/profile?symbol=IPAQ[full citation needed]
  7. ^ http://www.texasinvasives.org/plant_database/detail.php?symbol=IPAQ
  8. ^ Gunasekera Lalith. Invasive Plants, A Guide to the Identification of the Most Invasive Plants in Sri Lanka, Colombo 2009.
  9. ^ [1][dead link]
  10. ^ "Crispy Kangkong Recipe (River Spinach) - Filipino Recipes Portal". Pinoyrecipe.net. Retrieved 2014-01-13. 
  11. ^ Nutritional composition of traditional Thai foods used local vegetables
  12. ^ "Transmission: a Case Study of the Vuon-Ao-Chung Agricultural System on the Mekong Delta of Vietnam". Stanford University. 2002-04-28. Retrieved 2014-01-13. 
  13. ^ Sokeng, S.D.; Rokeya, B.; Hannan, J.M.A.; Junaida, K.; Zitech, P.; Ali, L.; Ngounou, G.; Lontsi, D.; Kamtchouing, P. (2007). "Inhibitory effect of Ipomoea aquatica extracts on glucose absorption using a perfused rat intestinal preparation". Fitoterapia 78 (7–8): 526–9. doi:10.1016/j.fitote.2007.06.011. PMID 17651914. 
  14. ^ Shivananjappa, Mahesh Mysore; Muralidhara (2012). "Dietary supplements of Ipomoea aquatica (whole leaf powder) attenuates maternal and fetal oxidative stress in streptozotocin-diabetic rats". Journal of Diabetes 5 (1): 25–33. doi:10.1111/j.1753-0407.2012.00210.x. PMID 22646693. 

External links[edit]