Diversity of the slippery zone microstructure in pitchers of nine carnivorous Nepenthes taxa

Abstract

Using a cryo-scanning electron microscope, we studied microstructure of the slippery zone in nine Nepenthes taxa. For N. fusca, N. macrophylla, N. mirabilis, N. ventricosa, N. dicksoniana, and N. veitchii, it was examined here for the first time. Three types of the slippery zone were distinguished among the studied taxa: (1) with well-developed crystalline wax coverage, (2) with greatly reduced wax coverage, and (3) without wax crystals. These data were combined with morphometrical measurements of the two pitcher zones primarily relevant to prey catching and retaining: the slippery zone and the peristome. In species with fully developed wax coverage, the slippery zone was longer and the peristome was narrower compared to those with reduced or lacking crystalline wax. We found statistically significant negative correlation between the relative length of the slippery zone and the relative width of the peristome. Based on the analysis of the relationship between the microstructure of the slippery zone and pitcher macromorphology, two main types of pitchers in Nepenthes are proposed: (a) traps based predominantly on the waxy slippery zone and (b) peristome-based traps.

Adhesion force measurements on the two wax layers of the waxy zone in Nepenthes alata pitchers

“…The fractured wax coverage in the intact waxy zone confirmed our previous findings13152027 about the composite structure of two superimposed wax layers on the top of the cuticle in N. alata pitchers (Fig. 1B).…”

“…The contribution of the waxy zone for trapping and retaining functions has been repeatedly reported1911121314151617181920. During the past decade, the role of water-lubricated peristome surface2122 and highly viscous trapping fluid2324 for prey capturing was discovered.…”

Oil adsorption ability of three-dimensional epicuticular wax coverages in plants

“…The waxy zone of the freshly harvested pitchers was used to get both UL and LL. The untreated pitcher surface bearing both wax layers26323336 was used as UL (Fig. 1a).…”

“…The total mount specimens with the inner pitcher surface facing up and fractured samples were examined in a scanning electron microscope Hitachi S-4800 (Hitachi High-Technologies Corp., Tokyo, Japan) equipped with a Gatan ALTO 2500 cryo preparation system (Gatan Inc., Abingdon, UK). Sample preparation and mounting are described in detail by Gorb and Gorb32 and Benz et al 33…”

“…The aim of the present study was to test whether the wax coverage of the waxy zone in the pitcher of the carnivorous plant Nepenthes alata is able to adsorb fluids. The wax bloom of N. alata was used here as a model plant system because it has been comprehensively studied previously in regards to its micro-morphology26323334 as well as physicochemical35 and material properties2636. The main functions of this pitcher surface are prey trapping and retention fulfilled through the reduction of insect attachment e.g.…”