Yarsagumba- a medicinal herb of long and illustrious history- is an Ascomycetes fungus closely related to the mushrooms. Cordyceps sinensis, the principal species of Yarsagumba under trade in Nepal, is an insect born parasitic fungus with fruiting body grown over the head of a caterpillar. While not actually a mushroom in the taxonomic sense, it has been regarded as, and called, a medicinal mushroom throughout history. Yarsagumba literally means summer plant and winter insect in Tibetan epithet (Yarsa: semi-animal and gumba: semi-herb). The name Cordyceps comes from the Latin words: cord and ceps, meaning "club" and "head", respectively. The Latin conjugation accurately describes the appearance of the club fungus, Cordyceps sinensis, whose stroma or fruitbody extend from the mummified carcasses of insect larvae, usually caterpillar larva of the Himalayan Bat Moth, Hepialis armoricanus. The parasitic fungus Cordyceps sinensis is variously known as Yarsagumba, Kira, Jeevanbuti in Nepali, Yarchakunbhu in Tibetan, Dong chong Xia Cao in Chinese, Caterpillar fungus in English and Cordyceps in botanical term; Sherpas also call them walking herb. In historical and general usage the term “Cordyceps” usually refers specifically to Cordyceps sinensis, although there are also many other closely related species. While Cordyceps sinensis is the most well known throughout the world, there are many other species in the genus Cordyceps in which modern science has found valuable medicinal properties as well. More than 100 species of Cordyceps fungus have been identified out of which 21 species are recorded in China, 30 species in Japan, and 12 species in UK, 7 species in India,31 species in Korea and 3 species in Nepal. The three recorded species of Cordyceps from Nepal have been C. sinensis (Berk.) Sacc., C. nutans Patolii, and C. nepalensis Zang et N. Kinnjo. It has been further reported that there are currently more than 680 documented species of Cordyceps in all six inhabited continents in a variety of habitats and feeding off of a range of hosts including plants, insects and arachnids, and even other fungi(such as truffles). This number is subject to rapid change, as what we know of this genus and the life cycles of its constituents treads into unfamiliar territory. It is obvious that as studies of related the species continue, the medicinal benefits of Cordyceps are not relegated to one species. Of these many varieties of Cordyceps, those presently being cultivated for medicinal purposes include: Cordyceps sinensis, Cordyceps militaris, Cordyceps sobolifera, Cordyceps subsessilus, Cordyceps ophioglossoides and others.