A universal glue: Underwater adhesion of the secretion of the carnivorous flypaper plant roridula gorgonias

Abstract

Glandular trichomes of the carnivorous plant Roridula gorgonias release a viscous resinous secretion. Its adhesion to hydrophilic and hydrophobic glass surfaces was measured in air and underwater. The underwater adhesion reached up to 91% (on hydrophilic glass) and 28% (on hydro-phobic glass) of that measured in the air. After being submersed for 24 h in water, trichomes did not lose their ability to adhere to both types of glass surfaces underwater. We assume that acylglycerides and triterpenoids, which have been demonstrated previously to be main compounds of the secretion, cause the predominantly non-polar character and the insolubility in water. The robustness of the secretion to a wet environment presumably enables the plant to maintain its trapping function also under humid conditions and during rainy weather.