Colocasia esculenta

Fast-growing evergreen perennial reaching 1m tall and wide. Hardy to UK zone 9. Insect-pollinated, self-fertile flowers; noted for attracting wildlife. Accommodates light sandy, medium loamy, and heavy clay soils, tolerating very acidic and saline conditions. Grows in semi-shade or full sun; prefers moist to wet soil across mildly acidic to neutral pH range.

Description

This plant has large flat leaves on the end of upright leaf stalks. It grows up to 1 m high. The leaf stalk or petiole joins the leaf towards the centre of the leaf. The leaves are 20-50 cm long. Near the ground a thickened rounded corm is produced. Around this plant their is normally a ring of small plants called suckers. Many different varieties occur. If left to maturity, a lily type flower is produced in the centre of the plant. It has a spathe 15-30 cm long which is rolled inwards. The flowers are yellow and fused along the stalk. There are many named cultivated varieties. Taro comes in two basic forms. The Dasheen type Colocasia esculenta var. esculenta and Colocasia esculenta var. antiquorum or the Eddoe type. The basic difference is the adaptation of the Eddoe type to storage and survival in seasonally dry places, while the dasheen type needs to be maintained in a more or less continuously growing vegetative stage. These are now recognised as separate species names.

Edible Uses

The corms are edible when thoroughly cooked and can be boiled, baked or fried much like potatoes. They work well in savoury dishes such as soups and curries, or in sweet preparations with coconut milk and sugar. They can also be dried and grated to produce a flour. The corm is a good source of starch with very small starch grains that are easily digestible; this starch is used to make baby food that is considered non-allergenic. Tubers are typically up to 30 cm long and about 15 cm in diameter. The corm must be properly cooked before eating to address the toxicity concerns noted below. Young leaves of some taro varieties are grown specifically for their nutritious foliage; they can be used to wrap other foods for baking or cooked as spinach, but must always be cooked first to destroy calcium oxalate crystals. The stems are also edible — peeled, cut into pieces and boiled in stews, they taste and look somewhat like celery.

Traditional Uses

The corms, petioles and leaves are all edible after cooking. The leaves are also dried and stored. The leaves are used for sarma in Turkey. They are rolled around a filling of rice or minced meat. The flowers are also cooked as a vegetable. CAUTION Some varieties burn the throat due to oxalate crystals. To remove these soak in baking soda for 2 hours then boiled for 60 minutes. Tamarind is used for this purpose in India. Fresh leaves can be stored for 4-5 days. Leaves and stalks can be dried and stored.

Medicinal Uses

The plant is antibacterial and hypotensive. A decoction of the leaves is drunk to promote menstruation. A decoction combined with parts of other plants is taken to relieve stomach problems and to treat cysts. In New Guinea, leaves are heated over a fire and applied as a poultice to boils. The sap of the leaf stalk is used to treat conjunctivitis. The scraped stem, combined with parts of other plants, is used to stimulate appetite. The plant is also used to treat wounds.

Known Hazards

Calcium oxalate crystals present in the leaves and corms require thorough cooking before consumption.

Distribution

It is a tropical plant. Taro grows from sea level up to about 2300 m altitude in the tropics. It grows well in humid places. It can stand damp soil and grow under light shade. It grows in wetlands. In Nepal it grows up to 1300 m altitude. It suits hardiness zones 9-12. In Yunnan.

Where It Grows

Afghanistan, Africa, Algeria, American Samoa, Andamans, Angola, Antigua and Barbuda, Argentina, Asia, Australia, Bangladesh, Barbados, Benin, Bermuda, Bhutan, Bolivia, Botswana, Bougainville, Brazil, Burkina Faso, Burundi, Cambodia, Cameroon, Canada, Canary Is., Cape Verde, Caribbean, Caroline Islands, Central Africa, Central African Republic, CAR, Central America, Chad, China, Chuuk, Colombia, Comoros, Congo DR, Congo R, Cook islands, Costa Rica, Côte d'Ivoire, Cuba, Dominican Republic, East Africa, East Timor, Easter Island, Ecuador, Egypt, Equatorial-Guinea, Eswatini, Ethiopia, Europe, Fiji, French Polynesia, FSM, Gabon, Gambia, Ghana, Grenada, Guam, Guatemala, Guiana, Guianas, Guinea, Guinée, Guinea-Bissau, Guyana, Haiti, Hawaii, Himalayas, Honduras, India, Indochina, Indonesia, Italy, Ivory Coast, Jamaica, Japan, Kenya, Kiribati, Korea, Laos, Liberia, Madagascar, Malawi, Malaysia, Maldives, Mali, Mariana Islands, Marquesas, Marshall Islands, Mauritius, Mediterranean, Micronesia, Mozambique, Myanmar, Nauru, Nepal, New Caledonia, Nicaragua, Niger, Nigeria, Niue, Norfolk Island, North Africa, North America, Northeastern India, Pacific, Pakistan, Palau, Papua New Guinea, PNG, Paraguay, Peru, Philippines, Pohnpei, Polynesia, Portugal, Puerto Rico, Rotuma, Rwanda, Sahel, Samoa, Sao Tome and Principe, SE Asia*, Senegal, Seychelles, Sierra Leone, Sikkim Singapore, Slovenia, Solomon Islands, South Africa, Southern Africa, South America, South Sudan, Spain, Sri Lanka, St Helena, St Lucia, St. Vincent and Grenadines, Sudan, Suriname, Swaziland, Tahiti, Taiwan, Tanzania, Thailand, Tibet, Timor-Leste, Tokelau, Togo, Tonga, Tunisia, Turkey, Türkiye, Tuvalu, Uganda, Uruguay, USA, Vanuatu, Vatican, Venezuela, Vietnam, Wallis & Futuna, West Africa, West Indies, West Papua, West Indies, Yap, Zambia, Zimbabwe,

Cultivation

Taro can be planted from cormels or from the top of the central corm. Other sections of the corm could also be used but this is not commonly done. Flowering of taro and seed production can lead to new cultivars. Flowering can be promoted by the use of gibberellic acid. The general growth pattern is for an increase in top growth, in terms of leaf number, leaf area and petiole length, to continue for about 6 months under tropical lowland conditions then for each of these to decrease and tuber storage to continue to increase. Corm weight increases significantly from 5 to 11 months. Starch content also increases with time but protein content declines over the corm development period. Taro can be grown under flooded conditions but root rots develop if the water becomes stagnant. For flooded cultivation, the land is cleared, ploughed, cultivated and puddled. The aim is to get a field that is flat with embankments allowing the impounding of water. Planting is done into 2-5 cm of standing water. For dryland taro, the soil is prepared by digging, unless a fresh bush fallow is used where the natural friability of the soil allows plants to be put into the undug soil in a small hole that is prepared. Plants are put into a hole 5-7 cm deep or deeper. Mulching to conserve moisture and reduce weed growth in beneficial. Setts from corms normally give higher yield than that from cormels. The greater leaf area and root production may be responsible for this. Setts of about 150 g are optimum. The time of planting is primarily determined by the availability of moisture. Planting is done shortly after the rainfall has become regular, if seasonally distinct wet and dry seasons occur. Higher rainfall, higher temperatures, and higher hours of sunlight, enhance production and determine seasonality of production. Evapotranspiration for flooded taro averages about 4 mm per day, ranging from 1.5 to 7.2 mm, with a total of about 1200 mm for the crop. Intermittent moisture can result in irregular shaped corms. Flooding has been found to be more effective than sprinkler irrigation, or furrow irrigation. Increased suckering, giving greater leaf area, seems to be the reason for this. Taro is sensitive to weed competition throughout most of its growth, but it is more critical during early growth up to 3 - 4 months. About 7-9 weedings are required, to keep the crop clean under tropical lowland conditions, where flooding is not used. Due to the decrease in height and leaf area towards the end of the growth cycle when starch accumulation in the corms is maximum, weed competition and weed control are again significant. Mechanical weeding needs to be shallow to avoid damaging the superficial taro roots. A range of herbicides have been recommended in various situations. Taro produces the highest dry matter yield under full sunlight, but it can still grow under moderate shade. Under shaded conditions it grows more slowly and develops less cormels. They require good moisture conditions and have little tolerance for drought. Taro residue has an allelopathic factor which can reduce the germination and growth of other plants, for example, beans. Taro tends to demand high fertility, and is responsive to additional NPK fertiliser. Higher doses of K increases starch content and higher doses of N increases protein content. Both N and K applications increase oxalic acid content of the tubers. Spacing affects total yield, and marketable, harvestable yield, of corms. Close spacing increases the corm yield per area, and the shoot yield per area, but decreases the corm yield per plant, and the contribution of sucker corms, to the yield. Where spacings of 30 cm x 30 cm are used, giving about 110,000 plants per hectare, a very large amount of planting material is required, which reduces the net return per unit of planting material. A spacing of 60 cm x 60 cm in more common. Wider spacings of 90 cm x 90 cm reduces overall yield.

Propagation

Seed is possible but this is a cultivated species unlikely to breed true, and plants rarely produce fertile seed. Division is the main propagation method, using suckers or corms. Small unmarketable corms weighing 60–150g from healthy, productive plants are typically used; larger corms can be cut into sections. Other planting material includes the apical 1–2 cm of the main corm with 15–20 cm of leaf stalk attached, side suckers growing from the main corm, or in Ghana, young suckers or mature setts cut from harvested corms. All planting material must come from healthy plants. Cormels are planted at a depth of 50–75 mm.

Other Uses

Taro can be used in agroforestry systems as a water-loving crop in wetland areas, improving soil moisture retention. It is also grown as an ornamental and used as animal fodder. The plant can provide some habitat value — corms and leaves may be consumed by wildlife, and dense foliage and leaf litter can offer shelter for invertebrates.

Production

Crops mature in 6-18 months. Yields of 5-15 tonnes per hectare are probably average.

Other Information

It is a commercially cultivated vegetable. It has been a very important food plant in Papua New Guinea. In some areas it is still important but in other areas it has declined because of insect and disease problems. Leaves are sold in local markets.

Notes

Leaf stalks have 3.1 mg per 100 g dry weight and 1.7 mg fresh weight of alpha-tocopherol (Vitamin E). There are 8 Colocasia species. Taro tru Taro tru (Colocasia esculenta ). This taro is grown by most people in the Southern Highlands even if only in small numbers. It needs to have a fertile soil, so people grow it around houses where they can compost their rubbish. In Tari they grow it on the fertile soil that they have dug out of the drains. Other people grow it in the moist fertile corner of their garden. The leaves and the underground corm are eaten. It is replanted from the top piece of the corm, It suffers badly from the black taro beetle and its larvae which eat the corm. Fortunately the two serious diseases that are ruining many taro crops on the coast (taro blight and taro virus) do not cause damage in the Southern Highlands. Taro tru can be recognised because the leaf stalk joins onto the centre of the leaf blade.

Nutrition

Synonyms

Also Known As

Aaki, Aba, Abalong, Achin, Aga, Akasi, Alo, Alu, Amadumbe, Amankani, Ang, Ange, Aro mwora, Arui, Arvi, Ba, Baal, Bahlip, Bal, Barbados eddoe, Bari, Biu o, Boka, Bon kachu, Bon van, Bo rui, Brobe, Bu laiche, Bwet, Chamadumpa, Chawa, Chemagadda, Chonque, Chou Bouton, Coco, Colulu, Curcas, Dagmay, Dalo, Danchi, Dehiala, Detaro, Dhopa, Diefele, Doko, Dow, Dsehi, Ebitekyere, Eddoe, Ega, Eze, Furedhdhe ala, Gaba, Gabha, Gabi, Gablos, Gadda kanda, Gahala, Gahula, Ghuiya, Ghuniya, Ghuya, Gimbi, Gingu, Golegez, Goodarree, Guagui, Gui, Gusum thaso, Gwamba, Gwasa, Henchichebu, Henru ke-ik, Hom, Hou min deng, Ikoko odo, Imo, Inhame, Ioth, Ishu koko, Jibabwai, Kachaloo, Kachalu, Kachchi, Kachu, Kake alo, Kake, Kalakasu, Kalo, Kandala, Karkal, Karkalo, Karoonay kilangu, Kattuchembu, Keladi, Kesavina beru, Khoai au nu'oc trang, Kieze, Kochai, Kochailal, Kochaimati, Kochu, Kochur mukhi, Koko, Kola kochu, Kolia kochu, Kolkas, Kollithalu, Kolokasi, Kopare, Kotak, Krachkoko, Kuchu, Kuhtak, Kukau, Lam pal, Langa, Lang henru, Lango, Lati, Lheng basar, Linsa, Logbui, Lubingan, Ma, Madere, Madumbe, Makoma, Mal, Malanga, Malangay, Malangu, Mane, Mangani, Maniango, Mattu midolodolo, Mbwet, Mi, Mileken, Moa, Mon nuoc, Mudhumbe, Mwitu, Nau, Ngaglin, Ngolo, Nkase, Numbole, Oburagoi, Ocumo culin, Oni, Opela, Ot, Pai, Papula, Pel kapa, Phueak, Pidaalu, Pindalu, Pidanlu, Pising, Pon-song, Pueta, Pwet, Qolqas, Quiquisque, Rebol, Sambu, Saonjo, Saonjorano, Saru, Satoim, Sawa, Seppankizhangu, Seru ara, Sewa, Shamagadde, Shamakkilangu, Shemakkalengu, Shembu, Shriew, Sola kachu, Sulur keladi, Suni, Suni agaga, Ta, Tabul, Tadala, Ta dogwa, Tagwamba, Taioba, Talas, Taleus, Talo, Tango, Taro kalo, Tato, Tayoba, Te taororo, Te taorourour, Thagong, Thalu, Thaso, Thaso gwswm, Thoks, Tikowounkofanti, Timoukan'te, Tra'w, Ttimba, Ttimpa, Tuka, Ule mankani, Utamchap, Vika, Woot, Yu-tao, Yekontenko

References (289)

• Taro references.
• Abbiw, D.K., 1990, Useful Plants of Ghana. West African uses of wild and cultivated plants. Intermediate Technology Publications and the Royal Botanic Gardens, Kew. p 29
• Achigan-Dako, E, et al (Eds), 2009, Catalogue of Traditional Vegetables in Benin. International Foundation for Science.
• Addis, G., et al, 2005, Ethnobotanical Study of Edible Wild Plants in Some Selected Districts of Ethiopia. Human Ecology, Vol. 33, No. 1, pp. 83-118
• Ali, A. M. S., 2005, Homegardens in Smallholder Farming Systems: Examples from Bangladesh. Human Ecology, Vol. 33, No. 2 pp. 245-270

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