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Food and drink biodiversity:

Seeds and nuts

Seeds are contained in fruits. A nut in the botanical sense is a seed inside an indehiscent, dry fruit with a hard covering (pericarp). Most fruits referred to as nuts in a cullinary sense are not true nuts in the botanical sense. For instance, pistachio and pecan nuts have lines of dehiscence and are thus not true nuts. The Brazil nut is not a true nut but a seed (a number of 'Brazil nuts' are contained within a large woody pod).

In a culinary sense, nuts have a hard covering with an edible kernel inside and seeds, by the time you get them to eat, do not have a covering that needs to be removed and are kernels that can just be eaten straight. Seeds from legumes are covered separately.  Grains are covered elsewhere and are also a type of dry fruit.

In this survey of the foods we eat, legumes, grains, seeds and nuts therefore make up the foods we eat that are derived from dry, non-succulent fruit or dry seeds in fruit. There is a separate page on fruits that we know as fruits in the food sense, i.e. succulent, juicy fruit.

Commercial species

Aleurites moluccana (Candlenut)

Family: Euphorbiaceae

The Candlenut tree in indigenous to SE Asia and grows to a height of about 12 to 15 m. It yeilds large nuts that are used in Indonesian and Malay cooking, either as whole nuts, as a paste, or using oil extracted from them. It is essential that the nuts are cooked or roasted before being consumed because they are poisonous when raw. Nuts have a high oil content (c 65%) and the oil is extracted from ripe, roasted nuts to produce cooking oil, and from half ripe nuts to produce lumbang oil, which is used for illumination. In southern Africa, Candle-nut trees are cultivated in Mpumalanga and KwaZulu-Natal and also grow wild as escapees from cultivation.

 

Anacardium occidentale (Cashew Nut) 

Family: Anacardiaceae

Cashew trees are indigenous to Brazil and were distributed round the world by Portuguese explorers in the 1500's. They are grown extensively in Mozambique and also in Maputoland (northern KwaZulu-Natal). Cashew nuts should not be eaten raw because they are surrounded by a very acrid, irritant oil - this oil is burnt off in the roasting process. Besides being very tasty, cashews are a good source of protein (about 17% by weight).

Anacardium occidentale (Cashew Nut)

Arachis hypogaea (Peanut) 

Family: Fabaceae

Groundnuts were domesticated by indigenous people in the region of Argentina and Bolivia over 4000 years ago. The seedpods mature underground, hence the name groundnuts. Peanuts are nutritious in that they contain 45-50% oil and 25-30% protein as well as having certain vitamins. However, peanuts infested with fungal aflatoxin and eaten in large quantities can cause liver cancer in people.

 

Bertholletia excelsa (Brazil Nut)

Family: Lecythidaceae

Brazil nut trees are indigenous to the Amazon rain forest in South America. Trees are about 45 m high and bear woody pods, each pod containing 12 to 20 hard-shelled seeds that we know as Brazil nuts. Most Brazil nuts are harvested from wild trees in Brazil and exported. The kernel of a Brazil nut contains about 67% fat and eating one nut is about the caloric equivalent of eating an egg! They are a good source of phosphorus and thiamin and contain some calcium.

Carya illinoensis (Pecan Nut) 

Family: Juglandaceae

Indigenous from south-eastern USA through to eastern Mexico. Pecans were harvested by indigenous North American tribes well before the arrival of European settlers in the 1500's. They were introduced to Spain in the 1600's and are now grown in all temperate regions of the world although the USA remains the main producer. Pecans have a high fat content (about 71%) but most of it is unsaturated (the more healthy type). They are an excellent source of phosphorus, thiamin, copper and zinc, and a good source of iron and potassium.

Castanea sativa (Sweet chestnut)

Family: Fagaceae

The indigenous distribution of Sweet chestnut extends from the Mediterranean to the Caucasus. It was introduced to Great Britain by the Romans. Chestnut cultivation involves selecting plants with large, tasty nuts and growing them clonally. The most common use of chestnuts is to roast them whole and then peel and eat them while they are still warm. Before roasting, it is important to cut an "x" into the flat side of the nuts to stop them from exploding. Chestnuts can also be boiled or steamed. In southern Africa, chestnut trees are grown in moist regions, usually in gardens and suburbs (e.g. Newlands and Rondebosch suburbs of Cape Town).

 

Cocos nucifera (Coconut) 

Family: Arecaceae

Coconut Palms are native to the Indo-Pacific Ocean region and grow at the top of beaches, at the limit of wave action. They are now grown in large plantations and are used for producing many products, such as coconut oil (from the white endosperm in the coconut), wine (toddy), spirit (arrack) and coir matting. The white endosperm is used in cooking and confectionery.

 

Corylus (Hazelnut)

Family: Betulaceae

There are about 15 species in the genus, with an indigenous distribution covering temperate regions of Europe, Asia and North America. The hazelnuts we eat are derived mainly from two species of tree: the European hazel Corylus avellana and the Filbert Corylus maxima. There are also hybrids between the two and hybrids with other Corylus species.  Hazelnuts are an excellent source of magnesium, iron, phosphorus, potassium and thiamin, and a good source of niacin. Hazelnuts are eaten raw or roasted and are also used extensively in chocolate making, baking and cooking.

Helianthus annuus (Sunflower)

Family: Asteraceae

Sunflowers originate from North America and are now grown extensively for their seeds which produce vegetable oil that is used in cooking, salad oils and margarines. The residue after oil extraction provides a high protein food source for livestock. 

Juglans regia (Walnut) 

Family: Juglandaceae

Native to the region in Eurasia extending from the Near East through to the Himalayas and on to Western China. Walnuts must have been harvested from earliest times but the earliest records of actual growing of orchards of walnut trees go back to classical Greek and Roman times. Besides the nuts, trees are also a source of high quality wood used for furniture and gunstocks. Growing of walnuts in Europe began in the 1500's. They are now grown worldwide and the largest production is from California.    Walnuts are an excellent source of zinc, copper, phosphorus and thiamin and a good source of iron and potassium. Uses Walnuts can be eaten raw or roasted. They are used as an ingredient in salads, baking and cooking.

Macadamia spp. (Macadamia Nut) 

Family: Proteaceae

The Smooth macadamia nut Macadamia integrifolia and the Rough macadamia nut Macadamia tetraphylla, both Australian species, have been cultivated for their nuts since about 1860.  Macadamia nuts are now grown in other parts of the world including Central America and South Africa. The fat content of Macadamia nuts is high, amounting to about 72%, primarily made up of monounsaturated fats. They are an excellent source of copper, magnesium and thiamin and a good source of iron and niacin. They are a popular snack, eaten be eaten raw or roasted and are also used in salads, baking and cooking.

 

Pistacia vera (Pistachio Nut)

Family: Anacardiaceae

Pistacia vera is a drought-resistant plant that grows wild in the Central Asian steppes and has been domesticated to produce plants with larger nuts. The nut is contained within a shell that splits open slightly, with an audible pop, when it is ripe. It has a greenish hue, which is unusual. Domesticated plants bear larger nuts than wild forms. Pistachio nuts are an excellent source of iron, magnesium, phosphorus, potassium and thiamin. Fat content stands at 54% by weight and is made up mainly of monounsaturated fats.

Pistacia vera (Pistachio Nut)

Prunus dulcis (Almond)

Family: Rosaceae

Almonds are believed to have been domesticated about 5000 years ago in the eastern Mediterranean region. Domestication involved hybridisation among a number of species and/or varieties and included selecting for plants with almonds that were not bitter. Bitter almonds contain a cyanide compound - eaten in small numbers your body is able to metabolize the compound rendering it harmless but if you eat them in large numbers you can get sick or die. Almonds are an excellent source of calcium, iron, riboflavin and Vitamin E. Calcium levels are higher than in any other nut. Almonds are eaten as a snack and used in many recipes.

Sesamum indicum (Sesame)

Family: Pedaliaceae

Believed to have been domesticated in India but by 600 BC it was being cultivated in the Middle East and came to be an important constituent in Middle Eastern foods (e.g. tahini and halvah). The seeds are eaten. They have a high oil content (40-60%) and are used to produce sesame oil. Sesame is cultivated on a small scale in southern Africa and also grows wild (naturalised).

 

Zea mays (Mielie seeds and Popcorn)

Mielie (corn) kernels are roasted and eaten as a snack. The seeds of the popcorn variety of Zea mays puff out into popcorn when they are heated up.

 
 

Non-commercial species introduced to southern Africa

Pinus pinea (Stone pine)

Family: Pinaceae

Originates from the Mediterranean region of Europe and grown in South Africa, mainly as a suburban tree. The cones produce large edible nuts, which in the Western Cape are referred to as dennepitjies or simply pitjies. Children collect them, crack them open and eat the soft white kernel. Pine nuts are also used in middle eastern cooking.

 

Indigenous species gathered in southern Africa

Information mainly from van Wyk and Gericke (2000)

Adansonia digitata (Baobab)

Family: Malvaceae

Seeds are eaten fresh or roasted.  They can also be ground into a powder used as a substitute for coffee.

 

Brabejum stellatifolium (Wild almond)

Family: Proteaceae

Produces brown, velvety, almond-like fruit. The seeds are toxic because they contain cyanogenic glycosides but these can be leached out by placing the seeds in sacks and running them under water for 'a long time'.

 

Leucadendron pubescens (Knokkers)

Family: Proteaceae

In the Clanwilliam area of the Western Cape, South Africa, the pea-sized seeds are collected from wild female plants and eaten as nuts.

 

Schinziophyton rautanenii (Manketti, Mongongo)

Family: Euphorbiaceae

Indigenous to N Botswana, N Namibia, SE Angola, W Zimbabwe, N Mozambique and marginally into South Africa, along the Botswana border. Has egg-shaped velvety fruit consisting of a thin fleshy layer around a thick, hard shell containing a nut. Both fruit and nut are edible and nutritious and have the advantage of being available for most of the year.

 

Sclerocarya birrea (Marula)

Family: Anacardiaceae

Indigenous to subtropical regions of Africa. Produces rounded, yellow fruit about 30 mm in diameter, containing a tasty, nutritious pulp as well as a pip with three oblong nuts that can be cracked open and eaten. The nuts also contain an oil that is used for various purposes including cooking, as a moisturiser, and as a baby oil. Marula is being commercially grown, mainly for the pulp, but not yet on a large scale.

 

Sesamum spp.

Family: Pedaliaceae

In addition to the cultivation of domesticated sesame Sesamum indicum (see above), seeds are harvested from wild Sesamum species in southern Africa (e.g. Sesamum capense and Sesamum triphyllum).

 

Strelitzia nicolai (Natal wild banana)

Family: Strelitziaceae

Seed capsules contain large black seeds with orange, oily arils. Seeds are ground into a flour, which is mixed with water and made into a fritter. The arils are pushed into the fritter and it is then baked over coals and then eaten. It is evidently a filling meal but not particularly tasty.

 

Ximenia spp. (sourplums)

Both species of Ximenia that occur in southern Africa have fleshy fruits with hard-shelled pips, each containing a tasty kernel.

 

Publications

  • Anon. 2002. Encyclopedia of Foods. A Guide to Healthy Nutrition. Academic Press, San Diego, California. 

  • McGee, H. 1991 (first published 1984). On Food and Cooking. The Science and Lore of the Kitchen. Harper Collins, London. 

  • Sauer, J.D. 1993. Historical geography of crop plants - a select roster. CRC Press, Boca Raton, Florida.

  • van Wyk, B.-E. & Gericke, N. 2000. People's Plants. A Guide to Useful Plants of Southern Africa. Briza Publications, Pretoria.  

  • Zohary, D. & Hopf, M. 1993. Domestication of plants in the old World - The origin and spread of cultivated plants in West Asia, Europe, and the Nile Valley. Clarendon Press, Oxford.

 

 


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