Forget rice and potatoes with your dinner - Britons need to start eating rare crops like breadfruit, cowpea and Bambara groundnut to help avoid global food shortages, a leading expert on plants has warned.

Professor Stephen Hopper, director of the Royal Botanical Gardens at Kew, in London, argues that the world is currently too reliant on just a handful of key species of edible plants for food.

He warned the combined threat of disease, climate change and lack of diversity in commercial crops has left the dozen staple species that provide the bulk of the global food supply - such as wheat, maize and barley - increasingly vulnerable.

He said farmers and consumers in Britain needed to increase the range of crops they grow and eat, to safeguard food supplies in the future.

His call comes as MPs will this week question farming groups on measures that can be taken to secure the UK’s food supplies over the next 40 years.

Professor Hopper predicted that crops such as breadfruit, a grapefruit-sized fruit that was grown in British colonies in the eighteenth century as a cheap foodstuff for slaves, Barbados cherries, Bambara groundnuts, cowpeas, and pigeon peas were among the crops that had potential to become future staples.

He said: “Famine has become an ever more frequent condition facing the world, particularly in heavily populated but marginal desertifying lands most susceptible to global warming.

“Food shortages are inevitable in such circumstances and will be exacerbated as the human population increases globally.

“The world is currently fed primarily from just a dozen species – around 80 per cent of the world’s food comes from those few plants used in commercial agriculture. Yet there are more than 30,000 edible plants known on the planet, so it is baffling we are so reliant on so few species.

“Diversifying the range of crop species is a sensible approach and could ensure food is available from alternative crops should staples fail in any given season.”

Professor Hopper spoke out after giving a speech about biodiversity to business and government officials at the 2009 Sustainability Summit organised by The Economist, in London last week.

He said that industrialised agriculture has led to the mass production of crops such as wheat, rice, maize, barley, oats and potatoes, which have become the main staple forms of food around the world, at the expense of other types of plants that were cleared to make way for these crops.

He warned that as global temperatures increase, many areas that currently grow these crops will become unable to sustain them.

Low genetic diversity in these staple food crops through generations of breeding has left them vulnerable to disease and pests.

The International Panel on Climate Change has already warned that food shortages will become far more common over the next 20 years.

They predict increasing levels of drought will hit some of the most important food exporting areas of the world, including southern Europe, western Australia, southern Africa, the Middle East and central USA.

Even in Britain, rising temperatures and new diseases will make it harder to grow crops in the arable areas of east and south east England.

Meanwhile, the rush to grow profitable non-food crops for biofuels has also led to fertile land no longer being used for food production.

Professor John Beddington, the government’s chief scientist, is so concerned about future food shortages he used his first major speech in the job to criticise the widespread switch from food crops to plants for biofuels.

Huge shortfalls in rice production over the past two years have led to food riots in several countries, while food prices have rocketed.

In 2007, wheat prices rose by more than 77 per cent while maize output in Europe fell by a quarter in 2008. Drought conditions in Australia have forced the authorities to search for alternative crop varieties.

Professor Hopper said that cultivating species such as breadfruit, grown on trees native to the South Pacific islands, and bulrush, whose roots were a popular carbohydrate among indigenous Australian aborigines, could also help preserve biodiversity.

He said: “During the past decade we have enjoyed a boom period, but our natural capital has been depleted at an astonishing rate.

“Narrowing the range of staples and reducing diversity, ultimately, is a high risk strategy in changing circumstances, with disastrous consequences for human health and, indeed, survival, in worst case scenarios.

“Commercial cropping requires removal of wild vegetation, destroying biodiversity. A new balance needs to be struck between land sequestered for commercial food supplies and other land uses, including biodiversity conservation if we are to live sustainably and enjoy a reasonable quality of life.”

Philip Hudson, chief horticultural advisor at the National Farmers Union, said: “Farmers are acutely aware of their responsibility to feed a world population that is set to grow to more than nine billion people by 2050. They will have to produce more food on less land.

“But the types of crops that farmers grow are demand driven, so the mix of crops we currently see in our countryside are there due to demand from consumers. It is only likely to change if there are similar changes in demand.”

EDIBLE PLANTS THAT COULD END UP ON YOUR TABLE

Breadfruit
Starch-rich, grapefruit-sized fruit that grows on trees on islands in the south Pacific ocean. Can be roasted, baked, fried or boiled and when cooked, tastes similar to fresh baked bread. In 1789, HMS Bounty was on a long voyage to collect breadfruit plants from Tahiti to cultivate in the West Indies, as food for slaves, when the mutiny broke out on board.

Bambara groundnut
Pulse from west Africa with seeds rich in protein and the essential amino acid methionine at levels higher than most other legumes. Still used as a traditional food source in parts of Africa and ripens in pods underground similar to the peanut. Can be eaten fresh or boiled after drying.

Barbados Cherry
Also known as wild crapemyrtle, it comes from a shrub that grows up to three metres tall and is covered in dense thorns. The fruit is bright red, contains up to three hard seeds and has a sweet and sour flavour. High in vitamin C.

Amaranth
Another traditional food in Africa, it is highly tolerant of arid environments. A grain crop, it contains up to 30 per cent more protein than other cereals while also containing other nutrients such as vitamin A and C. Its leaves can also be cultivated and consumed and in parts of Asia it is used to make soup.

Pigeon peas
Small bean that can be eaten as a fresh vegetable or dried and used to produce flour. Currently popular in India as split pigeon peas that are eaten in a similar way to chickpeas. Can be grown on marginal land and is highly drought resistant.

Cowpea
A nutty pulse and excellent source of protein that can grow in very dry conditions. It is currently available commercially and is related to the black-eyed pea.

Tamarind
A multipurpose tropical fruit tree that is well known for its use as a spice. The hard green pulp of the fruit can be eaten while still young as a savoury accompaniment or when ripened as a sweet snack.

Sunday Telegraph 1/3/09