Beads of water form on the surface of a leaf. This phenomena is commonly referred to as the 'lotus effect', due to the well-known self-cleaning properties of the Lotus plant. The beads roll off the surface of the leaf and take small particles of dirt with them.

The natural self-cleaning properties of the leaf are produced by a microscopically rough and super hydrophobic surface, which was discovered and patented by the botanist Wilhelm Barthlott. Nanotechnologies, including coatings, paints and other surface treatments, have been developed to mimic the lotus effect on clothes, products and buildings.