Development and regeneration ability of the wax coverage in Nepenthes alata pitchers: a cryo-SEM approach

The morphogenesis of the composite epicuticular wax coverage and regeneration ability of the upper wax layer in Nepenthes alata pitchers were studied using a cryo-scanning electron microscopy. Examination of pitchers of different ages revealed six stages in the wax coverage development. In the first stage, wax crystals resemble those found recently in mature pitches of N. dicksoniana and N. ventricosa. Platelets of the upper wax layer originate from broadened tips of stalks during the last developmental stage. Contrary to previous hypotheses, we found that wax crystals of both layers as well as the stalks connecting them are oriented perpendicularly to the pitcher wall. No changes in the height of the wax coverage were detected in 4-8 weeks after mechanical removal of the upper wax layer from mature pitchers on plants. This indicates that the wax coverage in N. alata pitchers is unable to regenerate.