taro

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taro
Taro (Colocasia esculenta)

Taro ( Colocasia esculenta )

Systematics
Order : Frog-spoon-like (Alismatales)
Family : Arum family (Araceae)
Subfamily : Aroideae
Tribe : Colocasieae
Genre : Colocasia
Type : taro
Scientific name
Colocasia esculenta
( L. ) Schott

The taro ( Colocasia esculenta ) is a species of plant in the arum family (Araceae). Taro is important to humans as a useful plant . The starchy rhizomes are consumed boiled or roasted.

Other names for taro are: taro, colocasia, taioba, eddo, eddoe, eddro, dasheen. In old reference works, such as Pierer's Universal Lexicon , there is also the spelling Tarro. In his work "The Naturalist in Nicaragua" (1874, Chapter V) Thomas Belt gives the name "Quequisque" which is common in Nicaragua . In the meantime, the name Malanga has established itself there via Quequisque , which actually refers to the similar Tannia . In eastern Ecuador , too , these two different genera are popularly referred to by the name "Papa china". In India he is known as Albi and in Japan as Sato-imo ( 里 芋 ). It is also known as the elephant ear plant . In the Philippines he is called Gabi .

Other species are also referred to as taro or elephant ear plants , the giant-leaved arrow leaf ( Alocasia macrorrhizos ), tannia ( Xanthosoma sagittifolium ), Cyrtosperma merkusii and other species of the genus Colocasia .

description

Taro rhizomes (tubers)
Colocasia esculenta flower

Taro is an evergreen , perennial , herbaceous plant that reaches heights of between 1 and 2 meters. The plants form ellipsoidal to club-shaped rhizomes that grow both vertically and horizontally in the soil. The potato-like rhizomes are fleshy and have an average diameter of 3 to 5 centimeters. In cultivated forms, the rhizomes can reach a diameter of up to 15 centimeters. They have a brown, rough shell with isolated, thin root threads and ring-shaped scars, which surround the whitish, often brownish to purple-spotted, to purple, starch-rich "meat". They can weigh 3.5 to 4 kilograms.

In addition to the rhizomes, taro forms long, horizontally spreading stolons . The stolons form thickened nodes .

The number of chromosomes is 2n = 26, 28, 30, 36, 38, 42, 44, 46, 48, 52, 58, 84 or 116. The large number of different chromosome numbers is due to the fact that taro chromosomes are very unstable during cell division and behave unexpectedly. The most common chromosome numbers are 2n = 28 or 42.

leaves

Detailed view of a taro leaf with recognizable leaf veins

Each plant forms 2, 3 or more, simple, arrow-shaped to heart-shaped, eccentric shield leaves stalked towards the base of the spider (i.e. the petiole sits on the underside of the spade) with rounded lobes. The sinus usually does not reach down to the base of the stem. However, normal leaves are also formed which have the stem approach at the base of the spread. The leaves can be hanging, horizontal, or upright with the tip pointing up or down on the stem. Sometimes the leaf base is also folded in on the obverse to become shell-shaped. The soft, leathery, smooth, velvety leaf blades are hairless and green, dark green, sometimes whitish or bluish-purple variegated , paler on the underside. There are also variations with blue-violet or slightly bluish, also with black-blue and orange-bluish leaves. The spreading surface is waxy and superhydrophobically water-repellent. The tip is acute to obtuse angled or pointed, occasionally also pointed.

The leaf margins are whole to bulky and often slightly wavy or partly bent. The spreads usually measure between 10 and 45 centimeters in length and 10 to 35 centimeters in width, but can also be significantly larger up to 80 by 60 centimeters. Due to their size, they are also known as "elephant ears".

The veins are whitish to violet and also brownish, but there are also variations with purple veins and edges. There are three primary major nerves, one centered toward the tip and two toward the basal lobes. The secondary lateral veins run obliquely from the basal point, parallel forwards and backwards, the tertiary ones are spread out like a network.

The normally green, upwardly tapering, upright to outwardly curved, smooth leaf stalks are arranged in a riding manner and between 20 and 80 centimeters long, in extreme cases up to 180 centimeters. The lower part, one-third to one-half, is tapered on the obverse, the trough edges are partly rolled up. The inside of the petioles is spongy (succulent) with air bubbles. There are also variations with partly orange as well as reddish or dark purple stems.

blossoms

As usual with the arum family, the inflorescence consists of an inflorescence stem, a bract ( spathe ) and the piston (spadix).

Usually a single inflorescence is formed on a 15 to 50 centimeter high stem. The lanceolate spathe becomes between 10 and 40 centimeters long and up to 6 centimeters wide. On the lower 4 to 5.5 centimeters it forms a green tube with a diameter of up to 2 centimeters, which then opens after the fruit has ripened. The spathe is cream-colored to golden yellow and hood-shaped, boat-shaped (cymbiform), with a curled tip. It usually surrounds the slightly protruding spadix on the back. It can, however, be shaped in various ways, bent back, rolled back, hanging backwards, twisted, rolled back and bent forward or protruding flat backwards.

The protruding spadix is ​​more than three times as long as the tube and measures between 12 and 16.5 centimeters. The spadix is ​​divided into a female and male section, these are separated by a sterile one.

The female section at the base, wrapped by the tube, is conically thickened and measures up to 3.5 centimeters. The female fertile flowers are green with a white pestle . The upper permanent ovary is unilokular (with an ovary tray) with 36-67 ovules and measures 1-3 mm in diameter. The lower section is also interspersed with sterile female flowers. The sterile flowers are cream-colored to yellowish and measure about 0.5 millimeters in diameter. The following, narrowed, sterile section, with sterile female flowers, is cylindrical and up to about 3 centimeters long.

The male section in the upper part of the spadix is ​​tapered and, at 4 to 6.5 centimeters in length, the longest section. The male flowers are pale orange with three to six intergrown stamens . The anthers have grown together to form a synandrium .

The unisexual flowers are bare-blooded (Achlamydeic).

The white-yellowish tip (appendix) of the spadix up to about 4 centimeters long has no flowers and is conically tapered. It is usually shorter than the male section, but it can also be longer or completely absent.

fruit

The fruits are green or reddish-orange, ellipsoid, about 3 to 5 millimeters by measuring berries . The ovoid, longitudinally ribbed, light yellowish-brownish seeds are between 1 and 1.5 millimeters long and about 0.8 millimeters wide; there can be up to 50 pieces per berry. The thousand grain mass is only 0.2 grams.

Locations and distribution

Global Taro Production Map

Because of the large leaves, from which a lot of moisture evaporates, taro needs a lot of water. Annual precipitation between 1500 and 2000 millimeters is optimal. The substrate should also be very moist. An average temperature of 21 ° C is ideal. The species is not frost-resistant. Taro normally grows at altitudes up to 1000 meters; the maximum height up to which taro can still thrive is 2700 meters in New Guinea . The species loves full sun locations and rich soils with a pH value between 5.5 and 6.5 (slightly acidic).

The largest stocks of taros are found in plantings in fields or water fields. Wild taro often forms large colonies in humid locations on rivers, canals or ponds. But there are also colonies in damp places in forests or in swamp areas.

Today taro is spread pantropically , but in most locations it was introduced by humans. Research suggests that the original, wild taro came from the Malay Peninsula , but that it also existed naturally in India, where the species dates back to 5000 BC. Was cultivated. From there, the species first spread throughout Southeast Asia , China and Japan. Other researchers claim that taro was originally found in New Guinea as well. Taro reached the Pacific when the islands were first settled up to 3500 years ago.

Cultivated taro from Japan and China arrived around 100 BC. BC to Egypt , was cultivated there and spread over the Mediterranean area. Around the year 1 the species spread along the east coast of Africa. From there taro got to West Africa and probably with slave ships to the Caribbean. In Florida , taro is considered an invasive weed .

use

Taro fields in Hawaii

Taro has been cultivated as a food crop on the Malay Peninsula for more than 7,000 years. Today taro is an important crop. In 1998 6.586 million tons of taro bulbs were produced worldwide. The worldwide cultivation area was 1.07 million hectares. Over 80 percent of the cultivated area is in Africa.

The starchy rhizomes of the plant are mainly used. Two thirds of these consist of water and about one third of carbohydrates, mostly starch . The protein content is seven percent of the dry matter . In the growing countries, however, almost all other parts of the plant are also eaten; leaf stems and leaves in particular are rich in protein (23 percent of dry matter). The rhizomes in particular contain calcium oxalate crystals (raphides), which disintegrate when boiled or heated.

Bowl with poi , the traditional Polynesian taro dish

In Hawaii , the plant species called kalo is one of the most important traditional crops. Poi , a paste, is made from the rhizomes . In some areas, flour is also made from the rhizomes; to do this, the tubers are treated with sulphurous acid , dried and then ground.

Taro is also important as fodder ; Excess aboveground plant parts are usually fed to cattle, in Hawaii these parts are also ensiled .

Medical

The grated taro rhizomes (tubers) are used in naturopathy in very cooling poultices for the treatment of, for example, bruises, strains and inflammations.

Diseases and pests

Especially in culture, taro is subject to frequent attacks by pests. A group of beetles (Coleoptera) called "taro beetles" should be emphasized . This is to species of the genus papuana in the family of scarab beetles (Scarabaeidae). In particular, these are Papuana woodlarkiana , Papuana biroi , Papuana huebneri and Papuana trinodosa . The adult beetles dig up to the rhizomes and eat them. As a result, the eaten rhizomes often rot, so that an infestation with taro beetles can lead to considerable damage in a culture. The female beetles lay their eggs close to the plant stem. The larvae feed on taro roots and dead plant parts, but do not yet attack the rhizomes.

Also feared is a fungal disease caused by Phytophthora colocasiae , the taro leaf rot . The fungus causes brown lesions on the leaves from which a yellowish liquid drips. The whole leaf dies within 10 to 20 days. The infestation of cultures regularly leads to crop failures of between 30 and 50 percent.

Several plant viruses also attack taro cultures. Important are the Taro-Large bacilliform virus (TLBV) defined by planthopper the type (Fulgoromorpha) Tarophagus proserpina is transmitted, the taro Small bacilliform virus (TSBV), the type Planococus citri from the family of mealybugs ( Pseudococcidae) and the Dasheen Mosaic Virus (DMV).

Systematics

Colocasia esculenta is one of about 20 species in the genus Colocasia . The type is very variable. It is distributed worldwide and has been modified in very different places by breeding or natural hybridization . Nevertheless, a division of the species into subspecies and varieties does not seem sensible.

Due to the strong - also genetic - variability, it is difficult to classify the taro within the genus Colocasia . A molecular genetic study from 1998 showed, for example, that Colocasia gigantea is now more closely related to species of the genera of the arrow leaves ( Alocasia ) and the gold scars ( Xanthosoma ) than to Colocasia esculenta within the same genus.

swell

Unless otherwise stated, the information in the Description chapter is taken from the sources Li & Boyce 2010 and Thompson 2000. For the chapters Distribution, Use, Diseases and Pests, Onwueme 1999 was the main source unless otherwise stated.

literature

  • Heng Li, Peter C. Boyce: Colocasia esculenta . In: Flora of China . tape 23 . Missouri Botanical Garden Press, St. Louis 2010, ISBN 978-1-930723-99-3 , pp. 73 f . (English, online ).
  • Sue A. Thompson: Colocasia esculenta . In: Flora of North America . tape 22 . Oxford University Press, Oxford 2000, ISBN 978-0-19-513729-3 (English, online ).
  • Inno Onwueme: Taro Cultivation in Asia and the Pacific . Food and Agriculture Organization of the United Nations, Regional Office for Asia and the Pacific, Bangkok 1999 (English, PDF; Part 1 , PDF; Part 2 ).
  • Peter J. Matthews: On the trail of Taro - an exploration of natural and cultural history . In: SENRI Ethnological Studies . tape 88 . National Museum of Ethnology, Osaka 2014, ISBN 978-4-906962-17-4 (English).
  • TK Lim: Edible Medicinal and Non Medicinal Plants. Vol. 9, Springer, 2015, ISBN 978-94-017-9510-4 , pp. 454-492.
  • Anton Ivančič, Vincent Lebot: The Genetics and Breeding of Taro. CIRAD, 2000, ISBN 978-2-87614-414-9 .

Individual evidence

  1. ^ Dudenredaktion (ed.): Duden - the large foreign dictionary. 2nd Edition. Bibliographisches Institut, Mannheim 2000, ISBN 3-411-04162-5 , p. 719.
  2. ↑ a b Michio Kushi : The macrobitic medicine cabinet. 4th edition, Ost-West Bund, 1990, ISBN 3-924724-32-6 , pp. 159-165.
  3. ↑ a b Ernest Small: Top 100 Food Plants. NRC Press, 2009, ISBN 978-0-660-19858-3 .
  4. ↑ Onwueme: 1999, p. 4.
  5. ^ Anton Ivančič, Vincent Lebot: Descriptors for Taro: (Colocasia Esculenta). International Plant Genetic Resources Institute (IPGRI), 1999, ISBN 92-9043-402-3 .
  6. ↑ Hans J. Ensikat, Petra Ditsche-Kuru u. a .: Superhydrophobicity in perfection: the outstanding properties of the lotus leaf. In: Beilstein J. Nanotechnol. 2, 2011, pp. 152-161, doi: 10.3762 / bjnano.2.19 .
  7. ↑ a b G. JH Grubben: Vegetables. Prota, 2004, ISBN 90-5782-147-8 , p. 208.
  8. ^ WL Wagner, DR Herbst, SH Sohmer: Colocasia. In: Manual of the Flowering Plants of Hawaii. University of Hawai'i Press, Honolulu 1999, ISBN 978-0-8248-2166-1 , pp. 1356 f.
  9. ^ Anton Ivančič, Vincent Lebot: The Genetics and Breeding of Taro. P. 84.
  10. ^ SJ Mayo: Flora of Tropical East Africa: Araceae. Balkema, 1985, ISBN 90-6191-322-5 , p. 5.
  11. ↑ Vincent Lebot: Tropical Root and Tuber Crops. Cabi, 2009, ISBN 978-1-84593-424-8 , p. 287.
  12. ↑ TK Lim: p. 461.
  13. ^ Thompson: 2000.
  14. ↑ Steve Lucas: Colocasia esculenta (L.) Schott. In: The Exotic Rainforest. Retrieved August 11, 2011 .
  15. ↑ Alan Davidson, Helen Saberi, Tom Jaine: The Oxford companion to food . 2nd Edition. Oxford University Press, Oxford 2006, ISBN 978-0-19-280681-9 , pp. 785 (English).
  16. ↑ Onwueme: 1999, p. 1.
  17. ↑ taro in Hawaiian Dictionaries , kalo in Hawaiian Dictionaries .
  18. ^ Li & Boyce 2010: p. 74.
  19. ↑ Nguyen Viet Xuan, Yoshino Hiromichi, Tahara Makoto: Phylogenetic Analyzes of Taro (Colocasia esculenta (L.) Schott) and Related Species based on Esterase Isozymes . In: Scientific reports of the Faculty of Agriculture, Okayama University . tape 87 , no. 1 , 1998, p. 133-139 (English, PDF ).

Web links

Commons : Taro  album with pictures, videos and audio files
Wiktionary: Taro  - explanations of meanings, word origins, synonyms, translations