the second major group of pitcher plants are the monkey cups or tropical pitcher plants of the genus "nepenthes". in the hundred or so species of this genus, the pitcher is borne at the end of a tendril, which grows as an extension to the midrib of the leaf. most species catch insects, although the larger ones, such as "nepenthes rajah", also occasionally take small mammals and reptiles. "nepenthes bicalcarata" possesses two sharp thorns that project from the base of the operculum over the entrance to the pitcher. these likely serve to lure insects into a precarious position over the pitcher mouth, where they may lose their footing and fall into the fluid within.