Is cordyceps a worm?
The caterpillar fungus, which the Tibetans refer to as the worm, is actually a fungus – Cordyceps sinensis. Or, to give the fungus its more elegant name, “winter worm, summer grass,” because its form varies with the seasons.
Cordyceps sinensis is found on the Tibetan Plateau, at altitudes of 3,500 to 4,500 meters. It grows in meadows and grasslands, and infection typically occurs in the late spring and early summer.
Cordyceps sinensis is a parasite that attacks the larvae of ghost moths and produces a club-shaped fruiting body (ascocarp) that protrudes from the ground. The fruiting body consists of a stroma (sterile tissue) and an ostiole (spore-bearing structure).
The stroma is the yellowish to brownish stalk-like portion that supports the ascocarp. It is composed of mycelium (a mass of hyphae – fine, threadlike filaments) that invade and kill the host larva.
The ostiole is the round, blackish structure at the top of the stroma from which spores are released. The ascocarp matures over a period of 2 to 3 months, and when it is fully grown, the fungus continues to produce spores for another 2 to 3 weeks.