this is the monster of the week incontered in Field Trip.
A giant subterranean fungal system. The organism manifests itself on the surface in the form of small white mushrooms that produce tiny spore "clouds" when stepped on. The spores contain a powerful hallucinogenic alkaloid, which also acts as a neurological inhibitor causing a state of narcosis. The combined psycho-neurological effect of the alkaloid prevents the victims, who were unlucky enough to step on the mushroom, from getting away while sinking deeper into the ground and being slowly digested by the digestive secretions of the organism.