Anacardium occidentale

Evergreen tree reaching 12 m by 20 m at slow growth rate. Frost tender, hardy to UK zone 10. Flowers pollinated by flies, bees, ants, and wind; self-fertile. Grows in light sandy, medium loamy, and heavy clay well-drained soils tolerating poor fertility. Adapts to mildly acidic through basic soil pH. Requires full sun, prefers moist soil but tolerates drought. Withstands strong winds but not maritime exposure.

Description

A spreading evergreen tree up to 7-14 m tall. It has spreading branches. The canopy can spread 12 m. The roots grow deeply and spread widely. The bark is rough. The trunk is 15-20 cm across. The leaves are alternate. The leaves are pale green and large. They are 10-15 cm long by 6-8 cm wide. They have fine veins. They are narrow at the base. The leaf stalk is 1-2 cm long. The leaves are shiny. The flowers are produced on the ends of the branches. They are red in colour. About 14 % of the flowers are both male and female and the remainder are male. Many of the flowers which contain female flower parts do not form fruit. The nut is borne below the "apple" which is really a fleshy stalk. The nut is kidney shaped. It is about 3 cm long.

Edible Uses

The cashew apple (fruit) can be eaten raw or cooked. It is juicy and refreshing but somewhat acidic, often astringent enough to leave a furry sensation in the mouth, and slightly fibrous. Light cooking removes much of the astringency. The fruit can also be dried or sliced alongside other fruits, juiced into a refreshing drink, or fermented into spirits. Red fruits are generally considered superior to yellow. The apple measures about 3 cm long. The seed (cashew nut) must be cooked before being removed from its shell. It has a pleasant, mildly sweet, bland flavour and is eaten on its own, salted, used in confections, or as the basis of savoury protein-rich meat-alternative dishes. An edible oil can be extracted from the seed, though its high commercial value means this is rarely done. Young leaves and shoots can be eaten raw in salads or cooked as a vegetable; they are used in Southeast Asia, picked during the rainy season and eaten fresh alongside hot, spicy dishes, though their astringency is too pronounced for most palates. Home processing of cashew nuts requires care due to caustic latex in the shell. Bury unshelled nuts in sand in a lidded, oven-safe pot dedicated solely to this purpose (latex residue will contaminate it for other uses). Roast at around 250°C for 10 minutes with windows open and good ventilation — the shells crack and caustic latex oozes out, potentially producing a caustic smoke that should not be inhaled. Remove the pot outdoors before opening the lid. Wear disposable gloves when handling the nuts, as oil residue may remain; wash thoroughly in water and detergent. Once the shell is safely opened, remove the kernel and peel off the thin brown papery skin. Any kernel that has come into contact with latex during processing is not edible and must be discarded. Unprocessed nuts can be stored for up to two years until enough have accumulated to make processing practical.

Traditional Uses

The fleshy "apple" is edible but acid until very ripe. It is used for jams and drinks. It is also candied, made into chutney and pickles. The nut is eaten after good roasting. They are also pounded and used as meal. The young shoots and leaves are edible. They are picked during the rainy season and eaten fresh with hot and spicy dishes. CAUTION The oil of the nut can blister the skin till roasted. The apple is used to make spirits.

Medicinal Uses

The leaves are febrifuge and are used in West Africa to treat malaria, and in India and Africa to treat toothache and gum problems. Leaves can be harvested at any time and dried for later use. The bark is astringent, rubefacient, and vesicant; research has also shown it to be hypoglycaemic, with the ability to reduce blood sugar levels. In Ayurvedic medicine the bark is used to detoxify snake bites and can be used fresh or dried as needed. Infusions of leaf and bark treat toothache and sore gums, while bark and leaf extracts and fruit juice are taken internally for diarrhoea. The fruit itself is antiscorbutic, astringent, and diuretic. Cashew syrup is used as a remedy for coughs and colds. Cashew apple juice is said to be effective against syphilis and is also used for cholera and kidney complaints. The fresh acrid juice inside the shell is vesicant and has been applied externally to remove warts and to treat ringworm, leprosy, corns, and cracked skin on the soles of the feet. It is toxic to various disease-causing organisms including Staphylococcus bacteria. The sap or bark extract is considered contraceptive. The gum is bactericidal, fungicidal, and lethal to worms and protozoa; it is applied externally for leprosy, corns, and fungal conditions. An infusion of the root acts as a strong purgative.

Known Hazards

The shell contains a caustic latex that can cause severe skin irritation and produces toxic fumes when heated. Nuts must be processed carefully before the kernel is safe to handle or eat; any kernel that has contacted latex during roasting must be discarded.

Distribution

It is a tropical plant. It suits the lowland tropics but will grow up to about 1200 m altitude. It only bears well in dry areas because of blight of the flowers. It needs warm frost free locations. It grows with temperatures between 22-26°C. A rainfall of 1750 mm per year is considered suitable but good yields have been obtained with rainfall of 750 mm. Wider spacing is needed in drier areas. It can grow on poor soils. It needs good drainage. It is drought resistant. It grows in the Sahel. In South India it grows up to 1000 m altitude. It can grow in arid places. It suits hardiness zones 11-12. In Yunnan.

Where It Grows

Africa, Amazon, Andaman Is, Angola, Aruba, Asia, Australia, Bahamas, Bangladesh, Belize, Benin, Bolivia, Brazil*, Burkina Faso, Cambodia, Cameroon, Cape Verde, Caribbean, Central Africa, Central African Republic, CAR, Central America, China, Colombia, Comoros, Congo DR, Congo R, Cook Islands, Costa Rica, Côte d'Ivoire, Cuba, Dominica, Dominican Republic, East Africa, East Timor, Ecuador, El Salvador, Europe, Fiji, France, French Guiana, French Polynesia, Gabon, Gambia, Ghana, Grenada, Guadeloupe, Guam, Guatemala, Guianas, Guinea, Guinée, Guinea-Bissau, Guyana, Haiti, Honduras, India, Indochina, Indonesia, Ivory Coast, Jamaica, Kenya, Laos, Lesser Antilles, Madagascar, Malawi, Malaysia, Marianas, Marquesas, Mexico, Mozambique, Myanmar, Nicaragua, Nigeria, North America, Northeastern India, Pacific, Panama, Papua New Guinea, PNG, Peru, Philippines, Puerto Rico, Sahel, Samoa, Sao Tome and Principe, SE Asia, Senegal, Seychelles, Sierra Leone, Singapore, Solomon Islands, Somalia, South Africa, Southern Africa, South America, Sri Lanka, St Lucia, Sudan, Suriname, Tahiti, Taiwan, Tanzania, Thailand, Timor-Leste, Tonga, Torres Strait, Trinidad-Tobago, Uganda, Vanuatu, Venezuela, Vietnam, West Africa, West Indies, West Timor, Yap, Zambia, Zimbabwe,

Cultivation

It is usually grown from seeds. Seeds germinate poorly and slowly. Only nuts which sink in water (or a solution of 150 g of sugar in a litre of water) should be planted. Seeds are sun dried for 2-3 days to improve germination. Seeds can be sown in a nursery then transplanted or more commonly are sown directly. Trees are spaced 7-10 m apart. The crop is cross pollinated mostly by insects. It can be propagated by air layering. For good production complete fertiliser or appropriate organic material should be applied. Pruning to shape the tree is often undertaken in the first 2 or 3 years. Cashews are often planted scattered in gardens or amongst other trees. Clearing under the tree prevents fire and makes finding nuts easier. Allowing nuts to fall before harvesting ensures only ripe nuts are collected. Resin in the cashew nut shell can damage hands and discolour the nuts. Roasting the nuts before removing the kernel avoids this.

Propagation

Seed is traditionally sown in situ, with germination typically occurring within 8–10 days. Seed stored for 4 months in open conditions has shown 100% germination; this drops to 50% after 10 months and zero after 14 months. Plants develop a long taproot and do not always transplant reliably. Propagation is also possible from cuttings of ripe wood taken at the end of the growing season, or by layering.

Other Uses

Because cashew grows well on poor sandy soils and in coastal conditions, it has been planted for erosion control. It has been intercropped with cowpea, groundnuts, and horsegram in India, and in Andhra Pradesh and Orissa, combinations with casuarina and coconut are common. Plants are often used as a support structure for cultivated vanilla. The fruit shell contains 45–47% oil with high heat resistance, making it useful as a lubricant and in varnishes, inks, termite-proofing treatments, and insulating coatings. The bark yields an acrid, thick brown resin that turns black on exposure to air, used as indelible ink for marking linen and cotton, as a varnish, a preservative for fishnets, and a flux for soldering metals. The stem produces an amber-coloured gum that is partly water-soluble, swelling into a jelly-like mass in water; it is used as an adhesive in woodwork panels, plywood, and bookbinding partly due to its insecticidal properties, and also in inks, dyes, and varnishes. The bark sap contains 3–5% tannin used in the tanning industry, and one of its components has insect-repellent properties. The toxic shell oil has high polymerizing and friction-reducing properties and serves as a waterproofing agent and preservative for fishing nets and woodwork against termites. Mixed with paraffin it improves control of mosquito larvae. It has been used in plastics manufacture and in speciality paints for ship keels, cement surfaces, and corrosion-prone environments. Distilled and polymerized, it is used in insulating varnishes, typewriter rolls, oil- and acid-proof cements and tiles, brake-lining friction materials, space-rocket lubricants, and inks. The reddish-brown wood is light and fairly hard but susceptible to termite attack; it is used for construction and general carpentry where dimensions permit, and wood pulp is used to make corrugated and hardboard boxes. The wood also makes good charcoal and fuel, and shell residue is commonly burned as fuel in cashew-nut-shell liquid extraction plants.

Production

Trees commence bearing after 3 years. Fruit production is seasonal. The fruiting season is normally October to January. Mature nuts are produced in 2-3 months. Yields of 80-200 kg per hectare of nuts are normal. Trees produce maximum after 10 years and trees last for about 100 years.

Other Information

A major world nut. At present mainly on research stations in Papua New Guinea. It is very important in India and common in Africa. The shell contains anacordolic which affects the salivary glands and can paralyse the jaw.

Notes

There are 8-11 Anacardium species. They grow in tropical America. It has antioxidant, anti-diabetic and anti-ulcer properties.

Nutrition

Synonyms

Also Known As

Abiba, Acado, Acajaiba, Acajou, Acaju, Acajuiba, Akadiya, Andima, Andi paruppu, Apu initia, Bajan, Balogo, Balubad, Bibbo, Buadju, Bu bisa, Bukagu, Bunga kesasar, Bu talakasa, Cadju, Cadjudje, Cadjuo, Cajou, Caju-manso, Caju-manteiga, Caju, Cajueiro, Casoy, Casuy, Cay dieu, Damrass, Dao lon hot, Darkase, Diboto, Gaju, Gajus, Geru bija, Hijli badam, Hijlibadam, Hizlee badam, Ialaguei, Ialike, Jambu erang, Jambu mede, Jambu mete, Jambu monyet, Janggus, Jidi-mamidi, Kacang mete, Kajoo, Kaju, Kaju badam, Kajus, Kajutaka, Kallarma, Kasau, Kashumavu, Kasjoe, Kasoy, Kassu, Kasuh, Kasuowo, Katae-ka, Katcha, Kollampazham, Kottaimundiri, Kuruti, Kusso, Mabotu, Mahabibo, Mak-mong-sang-yip, Mamuang himmaphaan, Mamuang letlor, Mamuang-Maruhao, Maranon, Mbibu, Merehe, Mindiri, Mkanju, Mkorosho, Mrano, Msololikoko, Mukejo, Muntha-mamidi, Munthiriparuppu, Mutua, Nkasu, Nkazuwa, Nkoloso, Nkorosho, Palamundiri, Parangi mavu, Pohon jambu monyet, Pucuk gajus, Saram, Simbangala. Supardi, Svaay chantii, Tabiba, Thiho thayet si, Udaracassa, Ya-koi, Yao dou, Yaruang, Yazawa

References (173)

• AAK, 1980, Bertanam Pohon Buah-buahan. Penerbitan Yayasan Kanisius, Jogyakarta. p 23
• 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 41
• Alexander, D.M., Scholefield, P.B., Frodsham, A., 1982, Some tree fruits for tropical Australia. CSIRO, Australia. p 13
• Ambasta S.P. (Ed.), 2000, The Useful Plants of India. CSIR India. p 37
• Anderson, E. F., 1993, Plants and people of the Golden Triangle. Dioscorides Press. p 202

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