Nepenthes, known as tropical pitcher plants or monkey cups, is a genus of carnivorous plants.The genus comprises roughly 140 species, and numerous 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 and the Seychelles; southward to Australia and New Caledonia; and northward to India and Sri Lanka.
Nepenthes adnata is a tropical pitcher plant endemic to Sumatra where it grows on mossy sandstone cliff faces above the Tjampo River. Insects seeking nectar from glands below the pitcher’s rim lose their footing and fall into a pool of acid and digestive enzymes in the bottom of the pitcher. Most struggle until they drown. A few manage to swim to the sides and succeed in scaling the wall into a zone of digestive glands, only to become hopelessly mired in sticky juice.