The colour and texture of a black truffle has been compared to the skin on a dog's nose - but it would have to be a dog that has been in many fights. The fungus is rarely as smooth as a dog's nose; rather, having grown around the roots of its host tree, it is gnarled, pitted and squashed like the nose of a bar-room pugilist. It seems appropriate, though, that the keen nose of a dog is used to sniff out truffles from their sub-terranean hiding places. Black truffles have been called the 'black diamond' of the kitchen but there are many varieties and few are worth eating. The most fragrant and delicious is the tuber melanosporum, which is also known as the Perigord truffle (although it grows wild in other areas of France as well as in other parts of Europe and is also being farmed commercially in Australia). Chinese black truffles, which grow in profusion in Yunnan province, are another variety. They lack the intense, distinctive flavour and aroma of the tuber melanosporum but resemble them in appearance; because they are abundant and cheap, there have been many reports of Chinese truffles being passed off as their far more expensive French cousins. The inside of a fresh black truffle is dark grey with white or pale-tan veins. The truffle turns jet black when it's frozen, which, if done correctly, will not affect its flavour. Tuber melanosporum has a longer season than that of the even more expensive Italian white truffles but both are considered winter 'crops'. Australian truffles, cultivated from tuber melano-sporum spores, grow at a different time of year to those in Europe, which means fresh truffles are available (from different hemi-spheres) for about six months of the year. Summer black truffles are another variety and their flavour and aroma is much milder than that of truffles grown in the colder months. Unlike white truffles, which lose their flavour and fragrance when exposed to too much heat so are shaved over a dish at the last minute, black truffles are usually cooked first. Canned (whole or in pieces) varieties may last longer but they are not as good as fresh truffles. Truffles are incredibly versatile; they are delicious cooked with meats and seafood (they make an especially wonderful pairing with scallops and lobster), or can be added to scrambled eggs.