What is the problem?
Although nowadays we have more choice of unusual foods than we used to, in a slow, steady way we are in danger of losing true variety, also known as "biodiversity". Environmentalists call the problem genetic erosion, saying it is the food equivalent of the destruction of the tropical rain forest.
Do any examples spring to mind?
You might be able to order tamarillos, lemon grass and mange tout all year round without any problem, but take a look at the increasing uniformity of our more familiar fruit and vegetables.
The first sign of genetic erosion is the almost total disappearance of certain species. Quinces and damsons, for example, were once commonplace in the UK. Now they are considered rare, and can be difficult to source unless collected in the wild.
Then there are disappearing varieties within one species. The National Apple Register for the UK, published in the early 1970s, recorded more than 6,000 native varieties, but just nine of these take the lion's share of commercial apple production.
Is it just a British phenomenon?
No. It is a worldwide problem affecting food crops. In India, for example, farmers used to plant up to 30,000 different varieties of rice. But the Agricultural Research Unit there estimates that within the next 10-15 years, just 10 varieties will be sown in 75% of the country's rice-producing area.
Is that the extent of it?
No, there are also concerns about the genetic similarity of new hybrid varieties of fruits and vegetables. Many of them have one common parent in their pedigree (the Maris or Pentland potato groups for example), which makes their genetic make-up similar as well as their eating qualities.
Does it matter if our food is more genetically similar?
It could matter. Genetically similar crops are vulnerable crops. The Irish potato famine of the 1840s was caused because growers planted potatoes bred from a few varieties. As a result the entire crop was decimated by one disease.
There is also an argument for preserving all the plant diversity that is developed over time. Each variety of fruit, vegetable or grain contains different genetic material that we may need in future. If these varieties are allowed to disappear, our food supply could become dependent on standard crops.
Apart from food security, why does biodiversity matter?
Taste and flavour is affected. The drive for developing new varieties is weighted towards ease of buying and selling - long shelf-life and so on - not because they taste especially good.
All too often it is the traditional, less commercial varieties of fruit and vegetable and breeds of meat that have more character and flavour. Taste a Worcester Pearmain or Ribston Pippin apple against a Golden Delicious and you can appreciate instantly the vastly superior flavour of the former two. Yet it is the latter which dominates our food supply.
There's also a nutrition argument. Take the vitamin C content in apples, for example, which differs according to variety. In every 100g of fruit, the Sturmer apple has 20mg of vitamin C and the Discovery has 16mg: both are traditional, non-commercial varieties. By comparison, however, the much more widely available MacIntosh Red apple has 3mg.
Why is this happening?
Many small seed and plant companies have been bought out by large multinational companies which are developing new strains of hybrid that guarantee high yields. These in turn are often dependent on the chemical products of the companies that bred them.
Our food supply has been radically altered by the growing powers of supermarkets. Over the past 20 years, supermarkets have brought in a new repertoire of foods: green beans from Kenya, Thai asparagus and so on. So we have not noticed the true variety of indigenous produce diminishing.
Supermarkets stipulate a specification for what they buy and this means a constant, unchanging supply of certain varieties which can be shipped around the country. This translates into a crop that matures consistently, and one that is tough enough to withstand travelling and packaging. So smaller supplies of more flavoursome and interesting varieties have been driven out by commercial rationalisation.
Any good news?
More people are waking up to what is going on. The European Parliament has tried to make it easier and cheaper to keep old varieties going, but these moves have been blocked by the European Commission.
In the UK, the Henry Doubleday Research Association has launched a scheme aimed at stopping the rot. It has made a list of a further 700 threatened vegetable varieties and is encouraging people to adopt them to secure their future.
The campaign group Common Ground, which acts to protect varieties, has run Apple Day for the past six years to draw attention to the grubbing up of traditional apple orchards and the loss of biodiversity. And, because of pressure from chefs, writers and consumers, supermarkets are offering small quantities of traditional or old-fashioned varieties of fruits and vegetables. But the overall emphasis on uniformity and standardisation continues unchecked.
What can chefs do?
Chefs understand better than most people the importance of variety when it comes to taste and flavour, and will know, for example, that potato salad with La Ratte or Pink Fir Apple potatoes will knock spots off one made with a boring white variety.
Chefs are not newcomers at tapping supplies of more flavoursome and unusual varieties. Consequently, they can have an important role to play in supporting biodiversity where possible.
This can mean encouraging smaller, local growers who might be prepared to grow a wider variety within a crop category by assuring them of a market. By naming varieties on the menu where possible (How does Baked James Grieve apple or gratin of Desirée potatoes sound?) chefs are able to highlight the culinary value of threatened old varieties and height- ten awareness of the biodiver- sity issue.