The water caltrop is any of the eight extant species of the genusTrapa, especially Trapa natans which is grown as a food crop. Its common names include buffalo nut, bat nut, devil pod, ling nut, mustache nut, singhara nut, and water chestnut, though this last name is commonly applied to Eleocharis dulcis.[1]
The species are floating annualaquatic plants, growing in slow-moving freshwater up to 5 metres (16 feet) deep, native to warm temperate parts of Eurasia and Africa. They bear horned fruits. Each fruit contains a single large seed. T. natans has been cultivated in China and the Indian subcontinent for the edible seeds for at least 3,000 years.
In feudal Japan, the fruits were used as substitutes for iron caltrops, an area denial weapon; they were sharp enough to penetrate the shoes of the period. The Japanese manufacturing group Mitsubishi takes its name and its logo from the plant. The Bengali name for the samosa or fried triangular pastry snack, shingara, is likewise the name of the plant.
Description
The water caltrop forms floating leaf rosettes up to about 50 centimetres (20in) across. It grows as an annual plant in shallow, slow-flowing fresh water, with a submerged stem up to some 2 metres (7ft) long and up to 6 millimetres (0.24in) thick, rooted in the bottom mud and bearing thin leaves. It prefers warm, nutrient-rich and sunny areas; the bottom is usually soft and rich in organic matter. The surface leaves are diamond-shaped, toothed, and up to 5 centimetres (2.0in) long and 6 centimetres (2.4in) wide. Their petioles (leaf stalks) are up to 21 centimetres (8.3in) long.[2]
The flowers have 4 white to pink petals up to 10 millimetres (0.39in) long, 4 sepals, 4 stamens, and one pistil. There are initially 2 ovules in the ovary but only one develops. The flowers are mainly self-fertilising, occasionally insect-pollinated.[2] The fruit is a nut (botanically a single-seeded drupe) with two to four barbed spines 12 millimetres (0.5in) long that develop from the sepals.[2] The Trapa natans plant contains an ellagitannin polyphenol called bicornin.[3]
The genus has an extensive fossil record, with numerous, distinctive species. Undisputed fossilized seeds have been found in Cenozoic strata starting from the Eocene throughout Europe, China and North America (though the genus became extinct in North America prior to the Pleistocene).[4] The oldest known fossils attributed to the genus are of leaves from CretaceousAlaska, referred to the species, T.borealis.[5]
Taxonomy
The genusTrapa and the type speciesT. natans were named by the Swedish botanist Carl Linnaeus in his Species Plantarum in 1753.[6] The generic name Trapa is derived from a late Latin word for a caltrop, calcitrappa, an area denial weapon.[2] The specific name natans is the Latin for swimming or floating, from the verb nato, "I swim".[7] As of 2023, there are eight recognised species, T. assamica, T. hankensis, T. hyrcana, T. incisa, T. kashmirensis, T. kozhevnikoviorum , T. natans, and T. nedoluzhkoi. There are eight named varieties of T. natans.[2] The Scottish surgeon and botanist William Roxburgh described Trapa bispinosa as a species in 1815, but botanists treat this as a variety of T. natans;[6][8] "T. bicornis" was described by the Swedish botanist Pehr Osbeck as a species in 1757,[9] but is treated as a synonym of T. natans var bispinosa.[10]T. rossica was described by the Russian botanist Viktor Nikolayevich Vassiljev and published by Vladimir Leontyevich Komarov in 1949; it is treated as a synonym for T. natans var natans.[11]
The water caltrop is widely distributed across Eurasia and Africa. In Europe, it is extinct in Spain and Sweden, and is absent from Portugal, the British Isles, Norway, and Finland.[2] It is so rare in Germany that it is listed as an endangered species.[12] In Southeast Asia, it is present in Sumatra and Java; it is found, too, across the Philippines and Japan.[2]
In eastern North America, it has been declared an invasive species from Vermont to Virginia,[13] and is classified as a noxious weed in Florida, North Carolina, and Washington.[14] As of 2020, both T. natans and T. bicornis were growing wild in US waterways.[15] In 1956 T. natans was banned for sale or shipment in the US, subject to a fine and imprisonment.[16] The law was repealed in 2020.[17]T. natans was introduced to Massachusetts around 1874 as a planting in the Harvard University Botanic Garden, and from there intentionally spread into nearby ponds and waterways.[18]
Parasite transmission
Eggs of the parasite Fasciolopsis buski, transmitted on the surface of T. natans fruits
Fasciolopsiasis is a disease resulting from infection by the trematodeFasciolopsis buski, an intestinal fluke of humans, endemic in China, Southeast Asia, and India. The fluke can be transmitted via the surfaces of water plants, generally T. natans fruits. During the metacercarial stage in their lifecycle, the larval flukes leave their water snail hosts, and swim away to form cysts on the surfaces of the plants. If infected plants are consumed raw or undercooked, the flukes can infect pigs, humans, and other animals.[19]
Interactions with humans
Use as food
The fruits and seeds are edible raw or cooked.[20] Archaeological finds from southern Germany indicate that the prehistoric population of that region may have relied significantly upon wild water caltrops to supplement their normal diet and, in times of cultivated cereal crop failure, water caltrops may have been the main dietary component.[21]
Water caltrop has been an important food for prayer offerings since the Chinese Zhou dynasty. The Rites of Zhou (second century BC) required worshippers to carry bamboo baskets of dried water caltrops (加籩之實，菱芡栗脯).[22]
In India and Pakistan, it is known as singhara or paniphal (eastern India) and is widely cultivated in freshwater lakes. The fruits are eaten raw or boiled. When the fruit has been dried, it is ground to a flour called singhare ka atta, used in many religious rituals, and can be consumed as a phalahar (fruit diet) on the Hindu fasting days, the navratas.[23]
It was possible to buy water caltrops in markets all over Europe until 1880. In northern Italy, the nuts were offered roasted, much as sweet chestnuts (Castanea sativa) are still sold today. In many parts of Europe, water caltrops were known and used for human food until the beginning of the 20th century. The plant has however become rare in Europe. Several reasons for its near extirpation exist, such as climate fluctuations, changes in the nutrient content of water bodies, and the drainage of many wetlands, ponds, and oxbow lakes.[21]
Water caltrop field, Taiwan
Boiled singhara (Trapa natans) for sale, Bhopal, India
In culture
In feudal Japan, water caltrop fruits were sometimes used as substitutes, tennenbishi for iron caltrops, makibishi.[24] Both types were sharp enough to penetrate the soles of the waraji sandals worn by warriors of the period.[25] The manufacturing group Mitsubishi takes its name, which means "three rhombuses" or "three water caltrops" (Japanese 三 mitsu, "three", 菱 hishi "water caltrop"), and its logo from the plant.[26] The plant and the fruit are called सिंघाड़ा shingara in Hindi. In Eastern India, the samosa (a fried triangular pastry) is called shingara.[27]
The company name Mitsubishi and its logo denote the fruit.[26]
Shingara, meaning water caltrop, is the Bengali name for samosas, fried triangular pastry snacks.[27]
References
↑"M.M.P.N.D. - Sorting Trapa names". www.plantnames.unimelb.edu.au. Retrieved 24 August 2022. Generally there is a lot of confusion throughout the world about the vegetable called "water chestnut". The first confusion is between the European Trapa and the Chinese Eleocharis. Then people get lost within each of those genera because common names have never been properly matched to stabilised botanical names.
↑R. W. Pemberton (2002). "Water Chestnut". In Van Driesche, R.; etal. (eds.). Biological Control of Invasive Plants in the Eastern United States. USDA Forest Service. Archived from the original on 2009-09-08. Retrieved 2007-07-14.
↑Pretzer, Xavid (2015). O-umajirushi: A 17th-Century Compendium of Samurai Heraldry. Cambridge, Massachusetts: The Academy of the Four Directions. p.ccxxx. ISBN978-0-692-37740-6.
↑Pauley, Daniel C. (2009). Pauley's Guide. Samantha Pauley. p.176. ISBN978-0-615-23356-7.
This page is based on this Wikipedia article Text is available under the CC BY-SA 4.0 license; additional terms may apply. Images, videos and audio are available under their respective licenses.
