truffle [key] [Fr.], subterranean edible fungus that forms a mutually beneficial (symbiotic) relationship with the roots of certain trees and plants. The part of the fungus used as food is the ascoma, the fruiting body of the fungus. The best-known truffles are the black, or Périgord Tuber melanosporum, and the white, T. magnatum, both found chiefly in W Europe. Their flavor is piquant and aromatic, and they have been esteemed as a delicacy from ancient times; recipes for their use are found in Greek and Roman writings.
The black truffles found in the forests of Périgord, France, have been highly regarded since the 15th cent., and their collection and cultivation is an important industry. Traditionally hunted with pigs, they are now mainly found by dogs, which can be trained to “point” for truffles and have the distinct advantage of not being truffle eaters. Black truffle cultivation has been somewhat successful since the late 20th cent.; it requires the inoculation of the roots of a seedling of its host plants, oak, hazel, and other deciduous trees, with fungal spores. Important black truffle producers are Spain, Italy, France, and Australia; all the black truffles from the last are farmed. The prized white truffle, harvested primarily in central and N Italy as well as in parts of S France, Croatia, and Slovenia, is more expensive and has not been successfully cultivated.
Besides the well-known white and black truffles, there are hundreds of other species, all mycorrhizae, fungi in a symbiotic relationship with plant roots. The summer, or burgundy, truffle, T. aestivum, a black truffle widely found in Europe, is most often associated with beech trees and is also prized for culinary use. T. indicum, a black truffle exported from China, where it grows on pine and chestnut roots, is regarded as inferior to the Périgord and summer truffles. The tasty Oregon white truffle, T. oregonense, grows on the roots of the Douglas fir tree, which is dependent upon the fungus for its mineral nutrition. Truffles are widespread in distribution and are found in a wide variety of habitats.
The desert truffles of Africa, the Mediterranean, and the Middle East (genera Terfezia and Tirmania) are typically found in arid and semiarid regions. They similarly grow underground. In the Mediterranean region, they are often found near Helianthemum species and other plants in the rock rose (Cistaceae) family, with which they grow symbiotically. Some desert truffle species are also prized as a delicacies and are collected in the wild. Their flavor and fragrance is generally less intense than European truffles.
Truffles and desert truffles are classified in the division Ascomycota, class Pezizomycetes, order Pezizales, families Tuberaceae and Terfeziaceae, respectively.
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