Nepenthes ampullaria is a widespread and very distinctive pitcher plant of the family Nepentaceae, occurring in Borneo, Peninsular Malaysia, Sumatra, Thailand, Singapore, New Guinea, and the Maluku Islands. This species has evolved away from carnivory and is partly detritivores, collecting and digesting falling leaf litter in its pitcher. The epithet ampullaria is derived from Latin word ampulla, meaning flask, in referring to the appearance of the pitcher. Nepenthes ampullaria is also known as Flasked-Shaped Pitcher Plant.
Nepenthes ampullaria often grows in tight clusters on muddy, moss-overgrown soil, in damp, shady kerangas forest or sundaland heath forest, peat swamp forest, degraded swamp forest, and paddy fields, from an elevation that ranges from 0-2100 m above sea level. It has climbing, light brown stem that may climb up to 15 m in height. The leaves are light green, 25 cm long and 6 cm wide. The pitchers are produced at the end of short tendrils of up to 15 cm long.
The flask- or urn-shaped pitchers are usually small, and rarely exceed 10 cm in height and 7 cm in width. The peristome is greatly incurved, with rarely produced upper pitchers. The color of the pitchers ranges from light green throughout to completely dark red, with many intermediate forms. In Peninsular Malaysia and Sumatra, the pitchers of Nepenthes ampullaria are green throughout or green with red speckles, while the red forms are mostly found in Borneo.
Nepenthes ampullaria is the only Nepenthes species that produces paniculate inflorescence.