Nepenthes stenophylla, or the narrow-leaved pitcher-plant, is a tropical pitcher plant endemic to Borneo. The species produces attractive funnel-shaped pitchers up to 25 cm high. It is listed as Least Concern on the IUCN Red List. Nepenthes stenophylla belongs to the loosely defined "N. maxima complex", which also includes, among other species, N. boschiana, N. chaniana, N. epiphytica, N. eymae, N. faizaliana, N. fusca, N. klossii, N. maxima, N. platychila, and N. vogelii.

Nepenthes boschiana, or Bosch's pitcher-plant, is a tropical pitcher plant endemic to Borneo. It is most closely allied to N. faizaliana. Nepenthes borneensis is considered a synonym of this species. Nepenthes boschiana has no known natural hybrids. No valid forms or varieties have been described. Nepenthes boschiana belongs to the loosely defined "N. maxima complex", which also includes, among other species, N. chaniana, N. epiphytica, N. eymae, N. faizaliana, N. fusca, N. klossii, N. maxima, N. platychila, N. stenophylla, and N. vogelii.