Native to the montane forests of Northen Sumatra, (typically 1800 - 2100 metres above sea level) N. jamban is distinct among Nepenthes in its particularly infundibular (funnel shaped) pitchers and its narrow operculum containing 20 - 30 visible glands concentrated at its apex. (glands not visible in these photos.
Top left is a terrestrial pitcher while top right and bottom are upper pitchers. (a particular Nepenthes species’ pitchers size and shape is usually affected by whether or not a pitcher is close to or on the ground or attatched to the climbing vine and therefore elevated. Lower pitchers tend to be larger, wider and more colourful while upper pitchers are more slender and less colourful, FYI. :))
Photo Credit: Alfindra Primaldhi