The Pitcher Plants: Family Nepenthaceae Dumort.: Nepenthes L. Sp. Pl. 2: 955. 1753.
Nepenthes is a group of carnivorous plants, commonly known as Pitcher Plant or Monkey Cup. It belong to a monotypic family, Nepenthaceae. Nepenthaceae are insectivorous plants that are easy to recognise because of the lidded pitchers borne on the end of a twining prolongation of the leaf. The leaf base itself is broad, further widening to form a laminar portion that then narrows to form the twining portion. The plants are dioecious, the inflorescences are racemes, the flowers are rather inconspicuous, and the seeds are very small. The family is distributed from Madagascar to New Caledonia [Source: APG III].
The genus comprises roughly 130 species, numerous natural and many cultivated hybrids. They are mostly liana-forming plants of the Old World tropics, ranging from South China, Indonesia, Malaysia and the Philippines; westward to Madagascar (2 species) and the Seychelles; southward to Australia and New Caledonia; and northward to India and Sri Lanka. The greatest diversity occurs on Borneo and Sumatra with many endemic species. Many are plants of hot humid lowland areas, but the majority are tropical montane plants, receiving warm days but cool
to cold humid nights year round. A few are considered tropical alpine with cool days and nights near freezing. The name monkey cups refers to the fact that monkeys have been observed drinking rainwater from these plants. [Source: Wikipedia]
The expanded part of leaf is developed from the leaf base, as in many monocots, the pitcher from the rest. How insects are trapped in the pitchers has long been unclear. Recent work suggests that the rim (peristome) of the pitcher is extremely wettable, and insects may aquaplane when they step on it, falling in to the pitcher below where they die and get digested; only when the rim is dry can insects walk on it easily, and then they may get trapped when they walk on to the wax-covered inner pitcher walls (Bohn & Federle 2004). Interestingly, the ant Camponotus schmitzi lives in close association with Nepenthes bicalcarata, and it can run across even the wetted rim. For the fauna of the pitchers, see Kitching (2000), while Pavlovic et al. (2007) discuss the physiology of lamina and trap. It has recently been found that some species of Nepenthes with particularly large pitchers capture the faeces of tree shrews (Tupaia montana) as they feed from glands on the inner surfaces of the lids (Chin et al. 2010). [Source: APG III].