The carnivorous syndrome in Nepenthes pitcher plants: current state of knowledge and potential future directions

Abstract

Nepenthes is the largest genus of pitcher plants, with its centre of diversity in SE Asia. The plants grow in substrates that are deficient in N and offset this deficiency by trapping animal prey, primarily arthropods. Recent research has provided new insights into the function of the pitchers, particularly with regard to prey tapping and retention. Species examined to date use combinations of wettable peristomes, wax layers and viscoelastic fluid to trap and retain prey. In many respects, this has redefined our understanding of the functioning of Nepenthes pitchers. In addition, recent research has shown that several Nepenthes species target specific groups of prey animals, or are even evolving away from a strictly carnivorous mode of operation. Future research into nutrient sequestration strategies and mechanisms of prey attraction would no doubt further enhance our knowledge of the ecology of this remarkable genus.

Figure 1

Scanning electron micrographs of some features of Nepenthes pitchers. (A) vertical section through peristome of N. villosa. Arrow points to position of extrafloral nectary at top of nectar duct. (B) Peristome of N. rafflesiana, showing anisotropic arrangement of epidermal cells. Arrow points in direction of pitcher mouth. (C) Lunate cells and wax plates inside upper wall of N. diatas pitcher. (D) Digestive glands towards base of N. fusca pitcher. In all cases, white bar = 100 µm.