Fungi have been known from the fossil record as far back in time as the Silurian period, 408 to
438 million years ago in the Paleozoic era. Fungal diversity had increased by the Pennsylvanian
period (286 to 320 million years ago) and included Basidiomycetes and Ascomycetes with some
fruiting bodies.1 That is, mushrooms have been part of the fungal diversity for around 300 million
years. Prehistoric humans probably used mushrooms collected in the wild as food and possibly for
medicinal purposes. The early civilizations of the Greeks, Egyptians, Romans, Chinese, and Mex-
icans appreciated mushrooms as a delicacy, knew something about their therapeutic value, and
often used them in religious ceremonies. With the widespread intentional cultivation of plants for
food, it was inevitable that this choice source of food, the mushroom, would eventually be cultivated
and not simply be picked in the wild. However, mushroom cultivation did not come into existence
until A.D. 600 when Auricularia auricula was first cultivated in China on wood logs. Other wood
rotting mushrooms, such as Flammulina velutipes (A.D. 800) and Lentinula edodes (A.D. 1000),
were grown in a similar manner,15 but the biggest advance in mushroom cultivation came in France
about 1600 when Agaricus bisporus was cultivated upon a composted substrate. In the Western
world, A. bisporus, commonly known as champignon or the button mushroom, increased steadily
in popularity from that early beginning and is today the mushroom that is produced in the greatest
quantity. In the past few decades, however, mushroom species (e.g., L. edodes and Pleurotus spp.)
that have long been popular in Asia and are produced there in large numbers have made and are
continuing to make inroads into Western markets. The Shiitake mushroom, L. edodes, is the second
most important mushroom, ranking just behind A. bisporus, and in 1999 the total world production
of L. edodes was estimated to be very close to that of the button mushroom. It has been estimated
that L. edodes may become the most popular mushroom grown in the world by 2019.9,37
Mushrooms not only provide a nutritious, protein-rich food, but some species also produce
medicinally effective products. Cultivated mushrooms are now an important agricultural product.