“Self-cleaning” Lotus

Why does the lotus plant, long held sacred in Eastern religions, always look so clean? German scientists now claim to have found the answer to this question that has intrigued biologists for ages. “Water-repellency of plant surfaces has long been known,” say the scientists W. Barthlott and C. Neinhuis. “But the self-cleaning properties . . . had been completely overlooked.” As explained in The Sunday Times of India, “the water droplets rolling off a lotus leaf carry away contaminating particles, thus cleaning the surface perfectly.” This is not because the surface is smooth. Seen under a microscope, the leaf has a rough surface of “knobs, folds and buttons” with “convex or dome-shaped water-shedding” profile. But added to this is the effect of the hydrophobic, or water-hating, wax crystalloids with which the plant is covered. The researchers say that this “lotus effect” drastically reduces the adhesion of water and dirt particles, and they add that the plant can regenerate waxes in spite of adverse environmental conditions. This, they say, makes the lotus’ natural efficiency far superior to man-made waterproof paint or washing detergents.