Spongy , morbid and fascinating .sx Kate Saunders views the growing process at the Partnership's Mushroom Farm , Leckford .sx It had never occurred to me that people could be passionate about mushrooms :sx in my dictionary , a fungus is defined as a " spongy , morbid growth " !sx But having spent a day at the Leckford Mushroom Farm , I can now understand the appeal of the tasty fungi .sx In growing rooms " as busy as the engine room on the QEII " , according to Mr Michael Ewin , Sales/Administration Manager , hundreds of thousands of white or chestnut-brown mushrooms sprout from compost , rapidly increasing in size as they feed on organic matter .sx In Mr Ewin's office , pictures of button mushrooms ( 40-60mm in size ) , and open and closed cup mushrooms adorn the walls .sx " Mushroooms are one of the most demanding products of all , " he says .sx " Although anyone can cultivate them , the critical thing is to grow them to meet the demands of the market 52 weeks a year .sx Retailers and wholesalers want quality and continuity .sx " You also have to be able to cope with the vagaries of the British consumer - they are unreasonable , and want more mushrooms on a Saturday , and very few in the early part of the week , for instance !sx " .sx Timing has to be perfect .sx Mushrooms start off in a button shape , then develop into closed cups .sx At that point the 'veil' , or mushroom skin around the edge , breaks and they become open cup mushrooms .sx Then the fungus turns into a large inverted umbrella shape .sx Each stage takes 24 hours , and Leckford growers pick mushrooms at the level of development required .sx Mr Ewin and Dr Bob Ross , Manager of the Mushroom Farm , have to be committed to the job .sx Their products are grown in a controlled environment , 365 days a year , and they think nothing of popping in to deal with emergencies or simply to check the mushrooms during the evenings or even on Christmas Day .sx Engineers , too , live nearby and are always prepared to rush back to the farm if necessary .sx The sales of mushrooms vary throughout the year , and Waitrose is a 'major customer' .sx Demand for mushrooms is much higher in the winter , as people buy large amounts for stews and casseroles .sx In the summer , demand tends to drop slightly .sx " These days , oyster and shiitake mushrooms are becoming more popular as additions to summer salads , " says Mr Ewin .sx " I am on the marketing and publicity committee of the Mushroom Growers' Association , aiming to promote the consumption of mushrooms within the UK .sx We produce videos , fact sheets and recipe leaflets .sx " In these diet-conscious times , people are responding to the fact that mushrooms are about 90 per cent vegetable protein , high in amino-acids and low in calories and sugar .sx " .sx Dr Ross and Mr Ewin guided me round the fungoid-smelling growing rooms to demonstrate the cultivation process .sx The compost used for the mushrooms is processed for up to four weeks at a local farm before arriving at Leckford .sx It is then fed out of the lorries on to a large yellow 'filling machine' which places a continuous slab of compost on to a tough fabric netting surface on cables .sx Mushroom spawn is then planted in the compost with special applicators .sx This spawn is made by specialised producers in lab conditions , and when stuck on to grain , looks as if the grain fragment is mouldy .sx The net , now loaded with compost and spawn , is winched into the growing rooms , which are closed up .sx The temperature is set at about 25C , with high humidity and no fresh air .sx Dr Ross explains :sx " The mycelium , or fungi spore , then grows through the compost as a white mould .sx It looks just like cotton wool .sx The mould is the fungus that we want - it's the beginnings of the mushroom .sx " There is an eight-day growth period , and then we put neutralised peat on top of the compost and mycelium .sx The grower's skill comes in deciding whether the fungus is at the right stage of growth .sx At this point , we drop the temperature to about 5C , lower the humidity and introduce fresh air .sx This dramatic change triggers off the growth of the fungus and mushrooms begin to form .sx " .sx Growing stage .sx The largest , and cheapest , raw material used in the operation is water .sx During the growing stage , mushrooms can be discoloured by water , but once a 'flush' , or batch of mushrooms , is picked , the peat is watered heavily over about three days .sx The growers' first sight before a flush appears is a tiny white pinhead , which develops into a larger , dome-shaped head .sx The Leckford farm is not merely a highly efficient mushroom production unit ; research is inextricably bound up with the whole process , and three smaller growing rooms enable Dr Ross and his team to experiment with different conditions which could increase the yield of both ordinary and exotic types of mushrooms without endangering the crop .sx A lab is also used to determine the ideal degree of moistness in compost .sx Dr Ross says :sx " It's said in the industry that once you're hooked on mushrooms you're never free of them - and I think that's probably true .sx I wrote my thesis on the subject of producing compost for mushrooms 15 years ago , and it is still a much debated subject today .sx Compost is such a complex mixture of organic materials , and its make-up can affect your yield of mushrooms dramatically .sx " .sx Dr Ross , who has worked at the Mushroom Farm since it opened , adds :sx " Over the years , mushroom yields have been going up and up as techniques for growing improve .sx In the mid-Sixties , a pound and a half of mushrooms per square foot was considered to be an excellent yield .sx Now we consider four and a half pounds in the same area to be disastrous .sx " .sx Dr Ross will continue his search for the perfect flush .sx But the rest of us may well be more tempted to try a tasty new type of mushroom , freshly plucked from a Waitrose shelf .sx But which type of mushroom , madam ?sx Kate Saunders looks at the characteristics of different varieties stocked by Waitrose .sx The biggest-selling mushrooms in Waitrose branches are the plain , closed-cup type , while open and flat mushrooms are gradually becoming more popular .sx The more exotic varieties such as oyster , which resemble the shape of an oyster shell ; shiitake , or 'forest mushroom' , which grow on certain types of dead or dying trees in the wild ; and chestnut mushrooms , known for their meaty , strong flavour , are slower to catch on with customers .sx Mr Alan Wilson , Assistant Central Buyer , fruit and vegetables , says :sx " We've introduced a distinctive yellow oyster which is milder in taste than an ordinary mushroom and has a soft and silky texture .sx The shiitake variety have quite a strong , almost musky , taste .sx We produced a leaflet on mushrooms about two years ago for our customers which included recipes and information about the different types .sx Although people are becoming more educated about exotic vegetables and Continental cuisine , they still prefer the more traditional mushrooms .sx " .sx Research by the Mushroom Growers' Association indicates that agaricus bisporus , the white cap mushroom including button , closed cup , open cup and open flat , accounts for about 98.6 per cent of sales .sx Mushrooms are good for you ; the shiitake variety were described as the 'elixir of life' by early orientals .sx Mushrooms contain more protein than most other vegetables , and are low in calories with only traces of sugar .sx They are also reputed to have diverse medical benefits such as the relief of gout symptoms .sx In common with other vegetables , their full nutritional value is obtained when they are eaten raw or lightly cooked .sx Shiitake mushrooms are said to be delicious shallow fried or baked in a little butter or oil and lemon juice to preserve the aroma and natural juices .sx They cost more than ordinary mushrooms because a crop of shiitake is much smaller than a crop of other types of the fungus .sx Oyster mushrooms are particularly popular in traditional Chinese and Indian cuisine .sx They often grow so closely together that they overlap like tiles on a roof .sx Cultivated oyster mushrooms can be fried , steamed , grilled , baked or deep-fried , and have a distinctive flavour .sx They also taste good raw with fresh herbs , yogurt and cream .sx According to the Mushroom Growers' Association , mushrooms are the most valuable horticultural crop grown in the UK .sx About 9 million households bought mushrooms in the 12 weeks ending mid-September 1990 , and about 1.4 per cent of mushrooms sold are exotic varieties .sx Wild and exotic .sx Wild and exotic breeds of the fungi are popular overseas .sx In Poland , pickers make a living supplying wild fungi to markets .sx In Italy and France , mushroom-seekers wander through the woods in search of romantically named species including porcini , chanterelles , shaggy inkcaps , puffballs , honey fungus , hedgehog fungus and horns of plenty .sx The difficulty in cultivating wild species often lies in their symbiotic relationship with the natural surroundings .sx In exchange for sugar from the plant , the fungus passes on minerals and nutrients it has extracted from the soil .sx This means that the fungus cannot live without the plant .sx Truffles , for instance , are inextricably bound up with the roots of oak trees .sx The French have devised a system of planting oaks in suitable places and inoculating their roots with the crop in order to get round this problem .sx Different types of mushrooms grow in different ways .sx While common mushrooms are induced to 'fruit' by being embedded in moist peat and chalk , with the humidity and carbon-dioxide concentration increased , oyster mushrooms fruit when the temperature is suddenly dropped and the light turned up .sx According to an article in The Economist , selective breeding of mushrooms is almost impossible because different strains cannot be crossed .sx One scientist is trying to overcome this by injecting genes directly into the mushrooms - although this is made difficult by their habit of keeping several nuclei in every cell .sx If you go down to the woods .sx .. Kate Saunders talks to Mr Stanley Carter , retired Director of Trading , Food , and mushroom expert .sx A group of villagers knocked on the door , proudly bearing a large basket full of mushrooms .sx " We're just on our way back from the woods , and we found these , " one of them said .sx " Perhaps you'd like to have a few .sx " .sx Mr Stanley Carter , retired Director of Trading , Food , and mushroom expert , glanced at the fungi and told his fellow villagers that they'd better come in .sx A quick look in a reference book confirmed his suspicions .sx He says :sx " They'd brought enough of that particular species of mushroom to poison the whole village .sx I told them that if they ate all those they'd probably die !sx " .sx These days , mushroom-pickers in the same village of Hemingford Abbots in Cambridgeshire always bring their finds to Mr Carter and his wife Galina for identification before eating .sx Mrs Carter says :sx " There is a French saying that you should only accept a mushroom or an identification of a mushroom from someone you can trust absolutely !sx " .sx The couple first became interested in mushrooms when two Russian friends pointed out a beautiful wild mauve mushroom on a country walk , and suggested that they cooked it .sx They subsequently became members of the thriving British Mycological Society .sx Although Mrs Carter says her interest in the fungi is purely gastronomical , Mr Carter - who first joined the Partnership when he was 16 - loves to wander through the woods near their home looking under fallen trees and undergrowth for unusual specimens .sx He is such an expert that he has even had one mushroom named after him .sx It is called Physarum bitanicatum Carter et Nann-Brem ( N E Nannenga-Bremekamp being a Dutch colleague who helped with the discovery) .sx Mr Carter recalls :sx " I was climbing a mountain in the Alps looking for areas where I thought unusual mushrooms might be found , when I discovered this specimen .sx I brought it home , studied it and analysed it .sx The discovery was verified and published .sx So far no one else has found another .sx " .sx Rows of neatly labelled small boxes full of mushroom spores and hefty tomes on fungi line Mr Carter's study .sx He also receives correspondence about mushrooms from all over the world and is communicating with the Professor of Mycology at Hong Kong University about one species .sx