Desiccation resistance of adhesive secretion in the protocarnivorous plant Roridula gorgonias as an adaptation to periodically dry environment.

To analyse the change of mass in the resinous secretion of Roridula gorgonias, we carried out long-term measurements using a computerised ultra microbalance. In contrast to the aqueous mucilage of other carnivorous flypaper traps, this water-insoluble secretion does not desiccate even in dead and formalin-preserved plants. We found no significant desiccation of secretory drops within 10 h of continuous weighing. After 100 days of the secretion exposure to dry conditions, only about 8% of the mass was lost. Interestingly, returning these samples to humid conditions resulted in a mass recovery to the initial amount. This property of the secretion is discussed as an ecological adaptation to the periodically dry Fynbos habitat of the plant.