PURITY OF THE SACRED LOTUS, OR ESCAPE FROM CONTAMINATION IN BIOLOGICAL SURFACES

The microrelief of plant surfaces, mainly caused by epicuticular wax c rystalloids, serves different purposes and often causes effective wate r repellency. Furthermore, the adhesion of contaminating particles is reduced. Based on experimental data carried out on microscopically smo oth (Fagus sylvatica L., Gnetum gnemon L., Heliconia densiflora Verlot , Magnolia grandiflora L.) and rough water-repellent plants (Brassica oleracea L., Colocasia esculenta (L.) Schott., Mutisia decurrens Cav., Nelumbo nucifera Gaertn.), it is shown here for the first time that t he interdependence between surface roughness, reduced particle adhesio n and water repellency is the keystone in the self-cleaning mechanism of many biological surfaces. The plants were artificially contaminated with various particles and subsequently subjected to artificial rinsi ng by sprinkler or fog generator. In the case of water-repellent leave s, the particles were removed completely by water droplets that rolled off the surfaces independent of their chemical nature or size. The le aves of N. nucifera afford an impressive demonstration of this effect, which is, therefore, called the ''Lotus-Effect'' and which may be of great biological and technological importance.