Cordyceps

The explanation of these names is that during the winter the fungus grows only inside its host. In the summer, however, it produces an exterior growth. So what appeared to be, and was, a live worm or larval insect can change into something which looks like and is a kind of plant. Tibetans believe that this is a real metamorphosis, and that the ‘insect-plant’ can move around as they hunt for it; but what has happened is that the fungus first consumes the nutrients provided by its host and only then, having thus killed it, sends up the brown stalk which is what can be seen above ground. The top of this stalk is thickened by spore-bearing globules and resembles a very small bulrush.