Nepenthes

Nepenthes (nᵻˈpɛnθiːz) is a genus of carnivorous plants, also known as tropical pitcher plants, or monkey cups, in the monotypic family Nepenthaceae. The genus includes about 170 species, and 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 (two species) and the Seychelles (one); southward to Australia (four) and New Caledonia (one); and northward to India (one) and Sri Lanka (one). The greatest diversity occurs on Borneo, Sumatra, and the Philippines, 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 were once thought to drink rainwater from the pitchers. Nepenthes species usually consist of a shallow root system and a prostrate or climbing stem, often several metres long and up to or more, and usually or less in diameter, although this may be thicker in a few species (e.g. N. bicalcarata). From the stems arise alternate, sword-shaped leaves with entire leaf margins. An extension of the midrib (the tendril), which in some species aids in climbing, protrudes from the tip of the leaf; at the end of the tendril the pitcher forms. The pitcher starts as a small bud and gradually expands to form a globe- or tube-shaped trap. The trap contains a fluid of the plant's own production, which may be watery or more viscous, and is used to drown the prey. This fluid contains viscoelastic biopolymers that may be crucial to the retention of insects within the traps of many species. The viscoelastic fluid in pitchers is especially effective in the retention of winged insects. The trapping efficiency of this fluid remains high, even when significantly diluted by water, as inevitably happens in wet conditions.