[4] While the name N. hookerae had first appeared in the literature four years prior to Beck's work, his concept of this hybrid involved a more complex cross (N. mirabilis × (N. rafflesiana × N. ampullaria)); it is considered a later synonym of N. × stewartii.
[1] This synonymy stood until John Muirhead Macfarlane's 1908 monograph, "Nepenthaceae", and the species are considered distinct today.
Taxon names are listed as they appear in Beck's monograph, including orthographic variants, though specific epithets derived from proper nouns have been decapitalised.
The infrageneric classification in "Die Gattung Nepenthes" follows that introduced by Joseph Dalton Hooker in his 1873 monograph, "Nepenthaceae".
Hooker placed N. pervillei in the monotypic Anourosperma, distinguishing it on the basis of its round seeds, and subsumed all remaining species in the second section, Eunepenthes.
[6] Beck kept the two sections created by Hooker (spelling Anourosperma as Anowrosperma), but divided Eunepenthes into three subgroups: Apruinosae, Pruinosae, and Retiferae, the last containing only N. lowii.