[18] Nepenthes alata has long been treated as a highly polymorphic species spanning all the major islands of the Philippine archipelago (with the possible exception of Palawan).

[19] Under this broad circumscription, N. alata was understood to have an altitudinal range of 0–1,900 m (0–6,234 ft) above sea level[17] and was recorded from, among others, the islands of Bohol, Camiguin, Cebu, Culion, Leyte, Luzon, Mindanao, Mindoro, Negros, Panay, Samar,[20][21] and Sibuyan.

[7] Under this interpretation, the more southerly plants previously referred to this species actually represent the newly resurrected N. graciliflora (the "typical N. alata" of horticulture; found on Bohol, Leyte, Luzon, Mindanao, Mindoro, Panay, Samar, and Sibuyan) as well as the newly described N. negros (Biliran and Negros) and N. ramos (Mindanao).

[7][17][23][25][26][27] Together these species form the so-called "N. alata group", being united by a number of morphological characters including winged petioles, lids with basal ridges on the lower surface (often elaborated into appendages), and upper pitchers that are usually broadest near the base.

Nepenthes eustachya from Sumatra was once considered to fall within the variability of N. alata, but this was based on a misinterpretation of type specimens; these two species do not seem closely related to each other.