Nepenthes are also known as tropical pitcher plants, or monkey cups, in the monotypic family Nepenthaceae. 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 (three) and New Caledonia (one); and northward to India (one) and Sri Lanka (one). Pitcher plants are several different carnivorous plants that have modified leaves known as pitfall traps. The families Nepenthes and Sarraceniaceae are the most species-rich families of pitcher plants.