itself, N. longifolia grows in a number of isolated patches and is sympatric with N. albomarginata, N. eustachya, and N. reinwardtiana. Plants resembling the type of N. longifolia are abundant along the road from Sibolga to Tarutung in North Sumatra. They differ from those of West Sumatra in a number of morphological features and may represent the poorly known N. beccariana. This taxon is sympatric with N. ampullaria, N. gracilis, N. rafflesiana, N. reinwardtiana, and N. tobaica. Nepenthes longifolia is not listed on the 2006 IUCN Red List of Threatened Species as the list follows Jebb and Cheek in treating N. longifolia in synonymy with N. sumatrana. The combined conservation status for both taxa is listed as Least Concern. However, recent studies have shown that these two taxa are distinct species. In 2001, Charles Clarke suggested a revised status of Vulnerable for N. longifolia based on the IUCN criteria. The habitat of this species may be threatened in the near future by fires deliberately started to clear forest for agricultural purposes. Related species Nepenthes longifolia is thought to be most closely related to N. sumatrana; the stem and lamina of these species are virtually identical in appearance. Nevertheless, N. longifolia can be distinguished from N. sumatrana on the basis of a number of significant and stable morphological differences. The tendrils on rosette leaves of N. longifolia are exceptionally long, reaching 110 cm, while those of N. sumatrana are not known to exceed 60 cm. As a result, the lower pitchers of N. longifolia are usually around 1/10 the length of the tendril, compared to 1/5 in the case of N. sumatrana. Although the lower pitchers on immature rosettes are similar in general morphology, the species differ in the shape of lower pitchers on rosettes sprouting from mature plants. Those of N. sumatrana are ovoid throughout, with an orbicular lid and the hip immediately beneath the peristome, and are contracted at an angle of 45° to the mouth. Those of N. longifolia are ovoid in the lower parts, having the hip around the middle and an ovate lid. In addition, the upper pitchers of N. longifolia do not give off a noticeable smell, whereas those of N. sumatrana have a sweet, fruity fragrance. In addition, the upper pitchers of N. longifolia are only infundibular in the lower parts, compared to the wholly infundibular aerial pitchers of N. sumatrana. Furthermore, the peristome