Encyclopædia Britannica, Ninth Edition/Truffle
TRUFFLE, the name of several different species of subterranean fungi which are used as food. The species sold in English markets is Tuber æstivum; the commonest species of French markets is T. melanosporum, and of Italian the garlic-scented T. magnatum. Of the three, the English species is the least excellent, and the French is possibly the best. The truffle used for Perigord pie (pâté de foie gras) is T. melanosporum. When, however, the stock of T. melanosporum happens to be deficient, some manufacturers use inferior species of Tuber, such as the worthless or dangerous Chœromyces meandriformis. Even the rank and offensive Scleroderma vulgare (one of the puff-ball series of fungi) is sometimes used for stuffing turkeys, sausages, &c. Indeed, good truffles, and then only T. æstivum, are seldom seen in English markets. The taste of T. melanosporum can be detected in Perigord pie of good quality. True and false truffles can easily be distinguished under the microscope.
Tuber æstivum, the English truffle, is roundish, in shape, covered with coarse polygonal warts, black in colour outside and brownish and veined with white within; its average size is about that of a small apple. It grows from July till autumn or winter, and prefers beech, oak, and birch woods on argillaceous or calcareous soil, and has sometimes been observed in pine woods. It grows gregariously, often in company with T. brumale and (in France and Italy) T. melanosporum, and sometimes appears in French markets with these two species, as well as with T. mesentericum. The odour of T. æstivum is very strong and penetrating; it is generally esteemed powerfully fragrant, and its taste is considered agreeable. Its price in England is two or three shillings a pound. The common French truffle, T. melanosporum, is a winter species. The tubers are globose, bright brown or black in colour, and rough with polygonal warts; the mature flesh is blackish grey, marbled within with white veins. It is gathered in autumn and winter in beech and oak woods, and is frequently seen in Italian markets, where it is sometimes sold for 12s. 6d. a pound. The odour of T. melanosporum is very pleasant, especially when the tubers are young, then somewhat resembling that of the strawberry; with age the smell gets very potent, but is never considered really unpleasant. The common Italian truffle, T. magnatum, is pallid ochreous or brownish buff in colour, smooth or minutely papillose, irregularly globose, and lobed; the interior is a very pale brownish liver colour veined with white. It grows towards the end of autumn in plantations of willows, poplars, and oaks, on clayey soil. Sometimes it occurs in open cultivated fields. The odour of the mature fungus is very potent, and is like strong garlic, onion, or decaying cheese. T. brumale, referred to above, grows in Britain. It is a winter truffle, and is found chiefly under oaks and abele trees from October to December. It is black in colour, globose, more or less regular in shape, and is covered with sharp polygonal warts; the mature flesh is blackish grey marbled with white veins. The odour is very strong and lasts a long time; the taste is generally esteemed agreeable. Cheeromyces meandriformis, which occurs in Britain, is some times sold for T. magnatum, the colour of the flesh of both species being somewhat similar. Scleroderma vulgare, the "false truffle," is extremely common on the surface of the ground in woods, and is gathered by Italians and Frenchmen in Epping Forest for the inferior dining-rooms of London where Continental dishes are served. It is a worthless, offensive, and possibly dangerous fungus. A true summer truffle, T. mesentericum, found in oak and birch woods on calcareous clay soil, is frequently eaten on the Continent. It is esteemed equal to T. azstivum. It probably grows in Britain. Another edible species, T. macrosporum. also grows in Britain, in clayey places under young beeches and oaks, on the borders of streams and roads, and sometimes in fields; more rarely it grows in plantations of willow and poplar. It has a strong scent of onions or garlic. Terfezia leonis, a famous truffle of Italy, Algeria, Sardinia, &c., resembles externally a potato. It grows in March, April, and May. Some persons eat it in a raw state, sliced, and dipped in oil or egg. It is not scented, and its taste is generally considered insipid or soapy. Sometimes an ally of the puff-balls, and therefore (like Scleroderma) not a true truffle, Melanogaster variegatus, is eaten in England and France. It has been, and possibly still is, occasionally sold in England under the name of "red truffle." It is a small ochreous brown species with a strong aromatic and pleasant odour of bitter almonds. When the plant is eaten raw the taste is sweet and sugary, but when cooked it is hardly agreeable. The odour belonging to many truffles is so potent that their places of growth can be readily detected by the odour exhaled from the ground. Squirrels, hogs, and other animals commonly dig up truffles and devour them, and pigs and dogs have long been trained to point out the places where they grow. Pigs will always eat truffles and dogs will do so occasionally; it is therefore usual to give the trained pig or dog a small piece of cheese or some little reward each time it is successful. Truffles are reproduced by spores, bodies which serve the same purpose as seeds in flowering plants; in true truffles the spores are borne in transparent asci or sacs, from four to eight spores in each ascus.
Spores of the chief European truffles. Enlarged 500 diameters. 1, Tuber æstivum; 2, T. brumale; 3, T. melanosporum; 4, T. mesentericum; 5, T. magnatum; 6, Chœromyces meandriformis; 7, Scleroderma vulgare; 8, Melanogaster variegatus.
The asci are embedded in vast numbers in the flesh of the truffle. In false truffles the spores are free and are borne on minute spicules or supports. The spores of the chief European truffles, true and false, enlarged five hundred diameters, are shown in the accompanying illustration. Many references to truffles occur iu classical authors. The truffle Elaphomifces variegatus was till quite recent times used, under the name of Hart's nut or Lycoperdon nut, on account of its supposed aphrodisiac qualities.