Nepenthes gracilis is a species of tropical pitcher plant common in lowland regions across South East Asia. The species is named for its slender pitchers, which are relatively demure but graceful in shape.
N. gracilis is characterised by its small pitchers which average around 10 cm in length. The lower pitchers have a ridge of hairs running down a vertical ridge but is otherwise unadorned. The peristome is remarkably thin in both the upper and lower ptichers. These pitchers range in colour from bright green to vivid red. The petioles of the basal rosette are sometimes reduced, resulting in a bunch of lower pitchers sprouting from the ground. The plants form sprawling vines that often drape along the ground or other foliage.
The species is adapted to capture Polyrhachis sp. ants, which are common to tropical rainforests. During rainstorms, the ants take shelter under the peristome, which when hit from above by a falling raindrop, flicks the ant into the pitcher.
The species grows in a range of lowland environments across South East Asia. In Singapore, I observed the species colonising a well drained and very sunny hillside in secondary forest. I also found the plants in West Sumatra, growing in a dark, waterlogged swamp forest. It can often be found alongside N. ampullaria.