Spotless Lotus

For an illustrated version, see pages 15-16 in The EnvironMentor, June-July 2015, vol. 3, no. 6.

In summer ponds and swamps, we can see white or pink waterlilies floating their leaves and flowers on the water. If you see leaves and white or pale yellow blossoms standing OUT of the water, however, those aren't water lilies: they're lotuses!

 

Our native lotus, Nelumbo lutea, is cousin to the "sacred lotus" N. nucifera whose behavior won it a place in the lore of the Middle East and Asia.

The ancient Egyptians noticed that the lotus blossom closes at night and sinks underwater, then re-emerges and reopens in the morning. It became a symbol of the sun, which vanishes each night but faithfully reappears each morning. Egyptian myths told that in the begining, a giant lotus had emerged from the primordial muddy waters and when it bloomed, the sun came forth! Lotus also represented re-birth after death, and images of lotuses decorated funeral urns and chapels. Lotus became the symbol of Upper Egypt. After powerful pharoahs had united Upper Egypt with Lower Egypt (symbolized by papyrus reeds), artists decorated their thrones, headdresses and monuments with both plants twined together.

In India, early Buddhists were more impressed by the way lotus leaves and blossums could arise spotless out of the muddiest water. It became the symbol of purity, representing the soul's progress from muddy materialism, through the waters of experience, into the sunshine of enlightenment. The Buddhist scholar Lalitavistara wrote, "The spirit of the best of men is spotless, like the lotus in the muddy water which does not adhere to it."

I did not find Native American lore or stories about N. lutea, but the plant provided such valuable food that traveling and trading tribes carried seeds from the plant's southeast origin throughout the plains states. They ate the large seeds, sometimes called "alligator corn." The starchy tubers (buried stems) are still enjoyed in soups and stews. They stay crunchy and absorb flavor from the broth.

 

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Waterlilies float their leaves and blossoms on the water, but lotuses rise above, emerging spotless from the muddiest pond or swamp. This "lotus effect" has fascinated engineers as much as scientists (or philosophers). How does it DO that?

Electron micrographs of the plants' waxy skin show tiny bumps that minimize the point of contact with bits of dirt or drops of water. Even at low angles, water droplets bead up and roll off, carrying with them any particles of mud or debris. This "superhydrophobic" (extremely water-repellant) property explains how they are "self-cleaning."

This property helps to protect water plants, and garden plants such as nasturtium (Tropaelum minor), from disease-causing fungi or algae. Some insects like butterflies and dragonflies, which can't groom all their body parts, also protect themselves this way. Nice trick if you can do it!

Now chemical engineers have figured out how to copy the Lotus Effect to manufacture items with surfaces that are water repellant and self-cleaning. Buildings can shed dirt and mold. Food containers, medicine bottles, and "lab-on-a-chip" biomedical devices can deliver every drop. Treated surfaces are even used to harvest dew for drinking water in arid seaside locations. Someday even clothing may take advantage of this biomimicry. Imagine coming home dry and spotless from a hike in wet, muddy fields! Thank the lotus.

 

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This column was inspired by an entry in the "Botany photo of the day" series, about lotuses

 

Various websites provided information about ancient Egyptian and Indian lotus lore.

 

For much more detail about the Lotus Effect, see "The Dream of Staying Clean: Lotus and Biomimetic Surfaces" (PDF)

For an illustrated version of this column, see pages 15-16 in the June-July 2015 issue of The Environmentor.