Nepenthes classification

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Danser placed Nepenthes rajah in the clade Regiae.

Nepenthes classification has been revised several times during the nineteenth and twentieth centuries.

[edit] Nineteenth century

The Nepenthes were first split up in 1873, when Joseph Dalton Hooker published his monograph on the genus. Hooker distinguished N. pervillei from all other taxa based on the fact that seeds of this species lacked appendages that were found to be present in all other Nepenthes (though greatly reduced in N. madagascariensis) and subsequently placed it in the monotypic subgenus Anurosperma (Latin: anuro: without nerves, sperma: seeds). All other species were subsumed in the second subgenus, Eunepenthes (Latin: eu: true; "true" Nepenthes).

A second attempt to establish a natural subdivision within the genus was made in 1895 by Günther von Mannagetta und Lërchenau Beck in his Monographische Skizze (German for Monographic Sketch). Beck kept the two subgenera created by Hooker, but divided Eunepenthes into three subgroups: Retiferae, Apruinosae and Pruinosae. Most contemporary taxonomists agree that Beck's groupings have little, if any, taxonomical value, as they were based on arbitrary traits not suitable for use as a basis for classification.

[edit] Twentieth century

Nepenthes taxonomy was once again revised in 1908 by John Muirhead Macfarlane in his own monograph. Oddly, Macfarlane did not name the groups he distinguished. His revision is often not considered to be a natural division of the genus.

In 1928, B. H. Danser published his seminal monograph, The Nepenthaceae of the Netherlands Indies, in which he divided Nepenthes into six clades, based on observations of herbarium material. The clades were: the Vulgatae, Montanae, Nobiles, Regiae, Insignes and Urceolatae. Regiae appears to reflect the relationships of its members quite well, although the same cannot be said for the other clades. Despite this, Danser's classification was undoubtedly a great improvement on previous attempts.

The taxonomical work of Danser (1928) was revised by Hermann Harms in 1936. Harms divided Nepenthes into three subgenera: Anurosperma Hook.f. (1873), Eunepenthes Hook.f. (1873) and Mesonepenthes Harms (1936) (Latin: meso: middle; "middle" Nepenthes). The Nepenthes species found in the subgenera Anurosperma and Mesonepenthes differ from those in the Vulgatae, where Danser had placed them. Harms placed the great majority of Nepenthes species in the Eunepenthes; Anurosperma was a monotypic subgenus, while Mesonepenthes contained only three species. He also created an additional clade, the Distillatoriae (after N. distillatoria).