The forgotten foods that could excite our tastebuds i5b1q

Just 12 plant species and five types of animal make up 75% of the world's food. At least 30,000 of the 350,000 known plant species on our planet are edible, according to the United Nations' Food and Agriculture Organization.

It is a woefully limited diet in the midst of such variety. Only 170 species of plant are cultivated for food on any significant scale. And around 60% of all the calories and proteins we obtain from plants come from just three grass crops – rice, maize and wheat.

There are huge risks in relying on so few plant species to feed the world. When a disease starts spreading in a particular crop variety, for example, it can surge worldwide. Often there is little genetic diversity within major crop species, leaving them even more vulnerable to disease. Climate change is also threatening our ability to grow these staple crops in many locations as they are not well suited to grow in the challenging conditions brought by greater droughts, flooding and rising temperatures.

There are some important lessons from history on the dangers of what happens if we rely on too few plant varieties for food. The devastating famine that hit Ireland in the late 1840s and 1850s, for example, resulted from the reliance on a single kind of potato by Irish farmers. When a fungal blight began destroying their crops, it wiped out a major food source for the country and over a million people died in the ensuing famine. But rather than learning from these mistakes, efforts taken in the mid-20th Century to feed the planet's rapidly swelling population have led to an over-reliance on just a few high-yield staple crops. The "Green Revolution" of the 1950s and 1960s saw agricultural scientists create varieties of wheat and corn, for example, that produced dramatically more yield per acre of land. While this has allowed farmers to continue feeding our rapidly growing population, it has also led to the spread of a mono-culture approach to agriculture.

The consequences of such mono-culture farming can be seen in a crisis that has struck one of the world's most familiar and popular fruits – bananas. There are over 1,000 varieties of banana, but 95% of the global trade in what is the fourth most important crop in the world has for decades relied on just a single variety, called the Cavendish. For the past three decades, however, a fungus known as Tropical Race 4 (TR4) - or Panama Disease – has decimated Cavendish bananas in over 100 countries, destroying crops in Latin America, Asia, Australia, the Middle East and Africa.

Efforts to rediscover desirable characteristics in wild plants – as has happened with the banana – are revealing a vast, untapped storehouse of genetic diversity present in uncultivated relatives of key crops. The vast number and diversity of wild versions of major global crops is what makes traits like disease resistance highly likely to be found here. Botanists at the Royal Botanical Gardens at Kew, London, for example, have recently unearthed an enormously diverse list of 7,039 species of edible plants from 288 different plant families, the majority of which could be used far more as food.

Often, however, these wild varieties are untamed and difficult to grow at any scale. Their domesticated relatives have had these wild qualities bred out of them over the centuries, making them easier to grow and harvest. This is why agricultural scientists have instead focused on cross-breeding these wild relatives with current crops or using techniques like gene editing to "cut and paste" the traits we might want.

“Diversity has always been the basis of breeders' work to develop better crops," says Harwood. "Gene editing offers a way to get useful diversity discovered in wild crop relatives into our current crop varieties.”

But there are two other categories of underused plants that are already used as a food source that could play a much bigger role in feeding us through the 21st Century and beyond.

One of these often over-looked food sources are "orphan crops" – locally domesticated and cultivated species with wider potential to become significant sources of nutrition for more people. Fonio, for example, is a nutritious West African millet with a handy resilience to drought. As well as feeding locals, it is now appearing on the menus of pioneering restauranteurs in places like the US.

Moringa (Moringa oleifera) is another intriguing orphan crop. Native to South Asia, but also grown in parts of Africa and South America, it is a dense package of nutrients, which could make it a new 'superfood'. And then there are pumpkin leaves. Known in Nigeria as ugu – but eaten all over Africa – these can be eaten fresh or dried, steamed or sauteed, or added to stews and stir fries to provide significant amounts of calcium, iron, potassium and manganese, plus a good dose of several vitamins.

Amazingly, the "discovery" by modern scientists of this treasure trove of traditional African plant species came about almost by accident. In the mid-1990s, WAC researchers were conducting surveys across sub-Saharan Africa to find out which indigenous trees locals – as opposed to outsiders – most valued. Rather than commercially important timber like mahogany, the experts were startled to find local people overwhelmingly chose indigenous fruit trees – species that were little known to modern science. The biological names of the trees was known, but little else, scientists at the WAC itted to New Scientist in 2009.

Since then, the WAC has helped spread the domestication across countries like Cameroon of the most highly-coveted of these wild Cinderella species, such as bush mango (Irvingia gabonensis) and safou (Dacryodes edulis), which is also known as African plum. Despite their names, neither is actually related to mangoes or plums.

Locals in Nigeria, Malawi and Cameroon prize these plants for a wide range of uses. As well as its fruit, the bush mango tree also produces fat and protein-rich nuts known as ogbono or dika nuts. Dried in the sun, these aromatic nuts can be ground to paste for making a local staple known as dika bread or, more prettily, Gabon chocolate. If powdered, they provide a thickening agent for traditional dishes such as ogbono soup or they can be pressed into a vegetable oil.

Another outpost of Far East crops flourishing in England is Namayasai Farm in Sussex, where Robin Williams and his wife Ikuko Suzuki have been growing yuzu, edamame, karashina (red mustard leaf), kabu (Japanese turnip), the minty herb shiso, negi (Japanese long onion), mitsuba (a Japanese take on parsley) and kabocha (a Japanese pumpkin) since 2004.

Across the Midlands of England, meanwhile, dozens of "exotic" crops are thriving in local allotments as part of the Sowing New Seeds project. This has brought together over 100 growers to cultivate plants native to countries as diverse and far-flung as Jamaica, India, Guyana, China, Pakistan, Japan, Zimbabwe and Ethiopia. "Talking to people growing non-traditional UK crops, we were surprised how well many grew in the UK climate," says Anton Rosenfeld, knowledge transfer officer at Garden Organic, who initiated the Sowing Seeds Project. “Some weren’t suited to our conditions, but there are some fantastic success stories.

Achocha, for example, absolutely thrives. It produces cucumber-like fruits with a wonderful flavour – a cross between minty cucumber and green pepper." Another success has been dudi or bottle gourd – a plant cultivated in the tropics for thousands of years.

Our global food market has already given consumers the opportunity to sample plants and crops from all over the world, but with the efforts of experimenting farmers, genetic scientists and expansion of under-valued orphan crops, our diets could get a lot more exciting still.