Nepenthes inermis
Description
Canopy epiphyte, climbing to at least 45 cm tall.
Leaves thinly coriaceous, sessile, those of short stems and rosettes unknown, those of climbing stems oblanceolate-spathulate to oblong, (5-)6.5-8(-12) by 1-1.6(-2.5) cm, apex rounded-acute, margin slightly revolute, base attenuate, clasping the stem for half its circumference, not auriculate or decurrent.
Fruits and seeds unknown.
Taxonomy
1 Nepenthes inermis is most likely to be confused with N. dubia or N. bongso which occur in the same general area of Sumatra and both of which can have similar proportions, indeed, all three species have been united by Tamin & M. Hotta under the name N. bongso. Nepenthes inermis is easily recognised by the absence of a ridged or dilated peristome and by the linear-oblong lid that overarches the mouth.
2. This species remains poorly known, and as yet the lower pitchers have never been collected. The remarkable upper pitchers lack a peristome, and have a very narrow lid. The tendril may or may not be coiled, an unusual habit — in the majority of species they are always coiled in upper pitchers. The pitcher fluid is said to be extremely viscous, forming long stringy droplets when the pitcher is upset. An unrelated species, N. eymae shares the same combination of infundibulate pitcher, narrow lid and viscous pitcher fluid. It has been suggested, and demonstrated in greenhouse-grown plants, that the infundibuliform pitcher and the highly viscous pitcher fluid allows rainwater to be shed from the pitcher without diluting or washing away the partly-digested contents. The weight of rainwater causes the pitcher to overbalance, shedding the water from the broad mouth, whilst the narrow shape of the lower part of the pitcher, and the viscosity of the column of fluid that it contains, prevents mixing with the supernatant rainwater (). A survey of 22 pitchers (under the name N. bongso) suggests that this species traps a very high proportion of dipterans (flies) compared to other Sumatran species surveyed ().