Nepenthes inermis is a tropical pitcher plant endemic to the Indonesian island of Sumatra. The specific epithet inermis is Latin for "unarmed" and refers to the upper pitchers of this species, which are unique in that they completely lack a peristome. Botanical history Nepenthes inermis was first collected on September 7, 1918, by H. A. B. Bünnemeijer on Mount Talang, at an altitude of above sea level. Two further collections were made by Bünnemeijer on Bukit Gombak on November 16, 1918, at and A fourth specimen was taken on April 26, 1920, from an elevation of on Mount Kerintji. This final specimen, Bünnemeijer 9695, was later designated as the lectotype of N. inermis by Matthew Jebb and Martin Cheek. Nepenthes inermis was first illustrated in an issue of De Tropische Natuur published in 1927. A year later, B. H. Danser formally described N. inermis in his seminal monograph "The Nepenthaceae of the Netherlands Indies". He wrote: "This new species is easily distinguishable from all others by the peculiar pitchers without peristome and with very narrow lid. Probably it is most nearly related to N. Bongso." Several of the specimens collected by Bünnemeijer were labeled with the local vernacular names galoe-galoe antoe and kandjong baroek. Danser noted that these originate from the Minangkabau language and are also used to refer to other species, but stated that their meaning was not clear to him. In 1986, Mitsuru Hotta and Rusjdi Tamin included plant material belonging to N. dubia and N. inermis in their description of N. bongso. In a 1993 study of Nepenthes prey and pitcher infauna, the same authors, together with M. Kato and T. Itino, identified N. inermis from Mount Gadut as N. bongso. Despite this taxonomic confusion, N. bongso differs considerably in pitcher morphology from N. inermis and is not easily confused with it. Description Nepenthes inermis is a climbing plant. The stem, which may be branched, reaches in length and is up to in diameter. It is cylindrical-triangular in cross section. Internodes are up to long. Leaves are sessile and coriaceous. The lamina is lanceolate-spathulate in form. It may be up to long and wide. It has an acute or obtuse apex and is gradually attenuate towards the base, which clasps the stem and is not decurrent. Three longitudinal veins are present on either side of the midrib. Pinnate veins are reticulate. Tendrils can be up to long