WORLD'S LARGEST FLOWER
The rafflesia is the world's largest flower. It can measure 42 inches across and weigh 15 pounds, much large than the plant that produces it. The five thick, leathery, red and orange pedals are a foot long and covered with molted, cream-colored warts. The cup-like diaphragm the pedals surround can hold six quarts of water. Within the cup are spiky sex organs. The flower has no visible leaves or stems and sits directly on the ground.. [Source: William Meijer, National Geographic, July 1985]
Rafflesia was discovered and named after Sir Thomas Stamford Raffles, an influential early 19th century British colonial leader in Southeast Asia. A famous hotel in Singapore is also named after him. Today the rafflesia is found only in western Borneo and Sumatra. Elephants, tigers and a little blue snake with a red head with a bite that kill you within minutes also live in the jungles where rafflesia is found.
There are several species of rafflesia . The largest is found in Sumatra. The plant of this species regularly produces a flower that is about 36 inches across. It is not known why the flower is so big. Perhaps it is because the plant gets all of its food from its host and can pour all its energy into making the flower.
Rafflesia Plant and Seeds
The rafflesia is a parasitic plant that digs invisibly into a host vine that is a member of the grape family. The host vine hangs down from the rain forest. In places where it hits the ground, during a predictable time, a lump appears in the vine's bark that gets bigger and bigger until it emerges as an orange globe. The globe continues growing until it becomes a cabbage-lik bud. When a bud opens into a flower the image is reminiscent of the film Invasion of the Body Snatchers. Except when the flower is blooming the entire Rafllesia is underground.
Rafflesia is called the "corpse flower" by locals because it smells like rotting flesh. Guides usually track it by smell not sight. The fetid odor is used to attract carrion flies which are the flower’s chief pollinator. There are fewer females flowers than males and the females are rarely fertilized. The fruit has been observed even less frequently than the flower. It is about six inches across and has a woody brown surface, and an oily, cream-colored flesh filled with thousands of red-brown seeds.
The vines on which the rafflesia grow are common but finding ones with rafflesia is a more difficult proposition. You need to look for a row of a half dozen or so buds of increasing size, bulging from the ground where the vines are covered by a thin layer of soil. Even if you find a bud that is no guarantee that you will see a flower. The timing of the bloom varies. Many animals eat the buds before they become flowers. Other rot on the vine. The flower wilts into a black gooey mess within four days after it blooms.
No one knows for certain how the seeds are transported so they can infect new vines. Some scientist believe that tree shrews and squirrels eat the fruit and distribute the seeds in their excrement. Others believe they are carried in the feet of large animals that puncture the vines by stepping on them, allowing the parasite to enter. They have speculated that one reason there are so few Rafflesia is that there are so few large animals to distribute the seeds.
Spikes at the center of the Rafflensia kerrii flower may help dispense the odor of rotting meat. Seeds for the Rafflesia arrnoldii and the slightly smaller Rafflesia keithii are distributed by treeshews and squirrels that eat the flower's cantaloupe-size fruit and excrete the seeds in their dropping as they scampers around on the vines that play host to the parasitic flowers.
Titan Arum Flower
The titum arum plant, which produces a huge trumpet-shaped bloom, is also regarded as the world largest and smelliest flower. The titan arum bloom is larger than the rafflesia but is officially an inflorescence not a flower because it consists of a spathe with many small flowers.
Describing the flower he saw, David Attenborough wrote in The Private Life of Plants, "Its spathe was shaped like an inverted bell with its point close to the ground. It was strengthened by long white ribs, like the spokes of a half-opened upside-down umbrella. Its upper margin was frilled. Outside, it was creamy green, but inside an intense and glowing crimson. From the center of this rose the huge spandix, like a wrinkled greyish spire. It was so out of scale with every other plant around it that its seemed to belong to another world."
The titan arum plant grows only in the rain forests of Central Sumatra. The six-foot-high, three-foot-wide bloom appears every four to seven years or so. The plant reproduces with the help of flies that are attracted by a smell released from the bloom that has been likened to a "dead crab on the beach with a sweet edge of burning sugar mixed with the sour smell of urine and ammonia." The smell is usually released in sudden burst at night.
The Arum Titan flowers for just three days. One bloomed at the Botanical garden in Basel, Switzerland produced a yellow pistol that was 2.27 meters high and tuber that weighed 13.6 kilograms. What was unusual was th the second blooming in November 2012 occurred less than 20 months after he first. One that bloomed in Meise near Brussels in July 2013, measured 2.44 meters
Adrian Higgins wrote in the Washington Post, “The titan arum, a plant type known as an aroid and distinguished by having the largest unbranched inflorescence on the planet. That’s botany-speak for one helluva flower, with a central column surrounded by a pleated ruff. It was a freak show of sorts — the thing is just big and otherworldly. When it was brought center stage to the conservatory on July 11, it was four feet high. When it opened on Sunday evening, it was eight feet high, and soon began pulsating heat and a notorious stench that was so nauseating that plant curator Bill McLaughlin said he couldn’t face dinner until about 11 p.m. that night. [Source: Adrian Higgins, Washington Post, July 22, 2013]
The obvious allure of this flower is its bizarre, exotic form taken to extreme size, no doubt. Subconsciously, it’s about sex and death, and I can’t look at Amorphophallus titanum without thinking of the old British Hammer horror films of the ’60s and ’70s. When will the bat fly out of enveloping spathe, I wonder? When will Christopher Lee be found standing behind it, flashing those fangs?
Titan Arum Plant
The titum arum belongs to the arum family of plants, Another arum plant, found in Southeast Asia and Borneo, features the world’s largest undivided leaf (See Rain Forest). Like other arums, the titan arum has a trumpet-shaped spathe with a spandix at its center.
The spathe of the titum arum is three feet across with its lip four feet above the ground. The spadix is nine feet tall. The titan arum produces a single leave that looks more like a small tree than a single leaf. Rising up to 20 feet and forming a canopy 15 feet across, the leaf produced food for the corm, a food storage organ formed from a hugely swollen underground stem, and every year its shrivel up and grows again. When the leaf decays, the plant rest for around six months and produces a flower.
The flower sprouts from the corm. It is roughly spherical in shape and has a circumference of five feet. It breaks easily because it is comprised mostly of vegetable fat, has little internal structure and has a delicate skin.
The flower can sprout any time of the year. Before it does the plant is hard to find because the corm is underground. At an unpredictable moment a giant bud emerges from the ground. It may rest above the ground for several days. Then suddenly at flow springs forth and grows several inches a day until t reaches its full height. After two days the flower collapses.
Titum Arum Smell
The flower produces the rotting-fish-like smells by raising its temperature several degrees above the surroundings area so and releasing oils that produce the smell when they vaporize in the heat. This attracts pollinators. It is not clear what the pollinators are. They may be carrion beetles or sweat bees. Scientist believe it has to be an animal that can cover the larger distances between flowers.
Higgins wrote: “The flower mimics death in the alchemy of its odor. “I can’t specify which dead animal,” McLaughlin said. (The smell wanes soon after the initial blooming). In its native Sumatra, the titan arum lures carrion beetles to pollinate its many pistils. Beyond the campy stage death, there’s the actual mortality of the flower. It opens for a day or two, ages rapidly and withers. We don’t know when its 90-pound tuber will flower again; perhaps in another eight years.
Titum Arum Smell and Seed
The spateh contracts inwards and twist around the lower pat of the spadix in such a way that a huge water-filled bag is created. Inside are the ovaries of the fertilized female flowers. The flower begins to swell at the basal stem, which increases in size and lifts the water-filled, pear-shaped bag higher and higher.
After a while the bag decays it reveals several thousand six-inch-long stems that form around a tall pillar. At the end of the stems are berries. After they turn bright read they are fed on by hornbills who distribute the seeds in their droppings.
The plant usually dies after its flower, which make it difficult to raise in botanical garden and explains why the plant is very rare and difficult to find in their natural habitat. The first European to record the titum arum was the Italian botanist Odoardo Beccaro who found it in 1878 while collecting plants in Sumatra. His team dug up the corm, which broke when two men carrying slipped and fell. Other corms were found and one was sent to Kew Gardens. In 1996, the flower from the plant bloomed for the first time in 30 years and 6,000 visitors came each day to see it.
Orchids and Fig Trees
The world's largest orchid is the Grammatophyllum speciosum Blume. Discovered in 1825 by botanist Carl Blume, it is found in rain forests in Southeast Asia, Borneo and Pacific islands such as the Solomon islands. One specimen found growing 150 feet above the ground in Borneo boasted of 25-foot-wide "crow's nest” with 50 spikes, five to 8 feet long, with each spike with 50 to 100 flowers.
Describing a fruiting fig tree un Borneo, David Attenborough wrote: "Monkeys scamper about in the branches sniffing every fig individually to decide from its perfume, whether it has reached perfection, and then if it is to their liking, cramming it into their mouths...Whole families of gibbons turn up and venture out on he furthest, most thinnest twigs, where heavy creatures find it difficult to move, fruit-eating birds flutter and squawk."
"The banquet doesn’t stop at the end of the day. New customers arrive at night. perhaps a loris, nocturnal primitive primate, plane-furred and wide eyed, will emerge from its hiding place, and giant fruit bats land and the branches with the a rustle of leathery wings."
See Orchids, Trees Under Rain Forestm World Topics
Carnivorous Pitcher Plants
Pitcher plants are carnivorous plants that have a sack-like, toilet-shaped pitcher that has fluid inside that it used to catch insects. They often grow as climbing vines. The pitchers have entrapped ants, spiders, flies mosquitos, cockroaches, centipedes and even tadpoles, scorpions and mice. The plants consume insects and other creatures to get nitrogen which often deficient in regions where they grow,
Pitcher plants are found in southern Malaysia, Indonesia, China, Vietnam, Cambodia, the Philippines, and New Guinea. A few species are found in Madagascar, Australia. New Caledonia, India, Sri Lanka, and the Seychelles. Many of most interesting and spectacular species reside in peninsular Malaysia, Sumatra and Borneo. Overseas pitcher plants are coveted by collectors. There is a large profitable market to supply them. Some varieties sell for $500 a piece.
There are more than 500 species of carnivorous plants. Many have evolved their carnivorous methods independently. One thing they have in common is that are found in areas where there isn’t much nitrogen or other nutrients in the soils and they get them from their kills.
Drinking from Pitcher Plants
Pitcher plants are sometimes called monkey cups because it is believed that monkeys drink from them. Scientist Paul Zahl, who wrote an article for National Geographic about the plants, didn't see any monkeys in the wild drinking from them but he did offer a pitcher plant to an orangutan who grabbed it out of his hand and chugged the water down in a single gulp.
While climbing Mount Ophir on Peninsula Malaysia, the 19th-century naturalist Alfred Russell Wallace occasionally drank from pitcher plants. He wrote the water was warm and drinkable and "we all quenched our thirst from these natural jugs” but they were "full of insects and otherwise uninviting." Zahl also said tried the water inside and said it was cooler than the water in his canteen. He also tried the water inside a pitcher plant which he said was good but warm. He carefully select pitchers that didn't have any dead insects inside.
Villagers in Brunei the water use as styling gel and hair conditioner. In other places the fluid is used as a burn ointment and a skin moisturizer and a treatment for eye inflamation. Most people who are in contact with the plant wince at the idea because the plant’s smell bad and the fluid contains too many insects and biting ants. Melanesian Islanders thought that pitcher plant contents smell like rat urine.
Pitcher Plant Growth
The “pitcher” of a pitcher plant is not a flower like many believe but is actually a modified leaf shaped like a sack and topped by a wide hood. It forms at the end of a tendril that grows from the tip of a leaf.. The inside surface of the hood as well as the swollen lip that surrounds the opening of the pitcher are pocked with nectar glands that produce the fluids that attract insects. Rain fills the pitchers with water.
David Attenborough wrote in The Private Life of Plants, "The process of pitcher formation starts when the tip of a leaf begins to extend into a tendril. This gains support for itself by twisting around the stem of another plant, usually making no more than a single turn. Its lip begins to swell and to drop under its own weight. Then quite suddenly, it inflates with air. As it balloons larger and larger, flecks of color appear in its walls. Now it begins to fill with fluid, its growth is complete, and a lid-like segment at the top opens. The trap is now ready to receive visitors.” [Source: David Attenborough, The Private Life of Plants, Princeton University Press, 1995]
Insects and Pitcher Plants
Pitcher plants lure prey to the "pitcher” with sweet-smelling nectar and fake flowers. Sometimes they even leave a trail for ants and other insects to follow to their doom. When the insect goes inside a pitcher to investigate it slips and falls into water inside the pitcher. Once inside the insect can't escape. Every time it tries to climb the pitcher walls it slip back down into the fluid at the boot of the pitcher, where it is sometimes stunned by chemicals. Eventually the insect drowns.
The inside of the pitcher is incredibly slippery. The upper part of the pitcher, below the nectar source on the underside of the pitcher’s lid, is covered by a slippery, waxy material that clings to the insect’s feet. Some pitcher plants have little bristles or downward-pointing hairs near the opening of the pitcher that acts like a fence to keep the insects in.
Many of the victims are flies and mosquitoes. Typically they land on the lid, and as they search for more nectar make their way over the edge slip on the walls. The waxy material of the walls breaks off as the insect tries to adhere to it and falls in the water. As the victim struggles it stimulates glands in the pitcher plant that excrete digestive acids..
Insects with a Symbiotic Relationship with Pitcher Plants
Living within the pitcher plants are a variety of insects that feed on the detritus in the fluid and in turn supply the plant with oxygen and nutrients derived from their bodily waste. These insects can break up large victims into small pieces that are easier to digest. Some pitcher plants are host to some large creatures. One species is home of half-inch-long crab.
Some moths and wasps are specially adapted to walk up and down the inside of the pitcher plant. Some deposit their eggs inside the pitcher (with the larvae feeding on the pitcher's prey) and help the plants reproduce by transporting pollen from plant to plant. Mosquito, gnat and fly larvae also live in the fluid, some of which battle each other over territory in the fluid. Some attract birds that are forced to feed on nectar in such a way that their excrement helps provide nutrients for the plant.
One species of ant, the schmitzi ant, is unaffected by the chemicals in the pitcher and is able to climb the walls and even rescuesof other insects. Describing rescue of a cockroach by these ants, Eric Hansen wrote in Discover magazine, “The rescue was slow and orderly. Once the diving schmitzi ants brought the cockroach to the edge of the reservoir, the other ants helped carry the wounded insect up the slippery vertical wall...The ants looked like a group of energetic six-legged rock climbers. With toenail-like crampons...the arduous two-inch ascent from fluid to resting place took more than an hour.” Once rescued the ants ripped the cockroach apart and ate it. Unconsumed bits were thrown back in the pitcher where they were consumed by mosquito larvae.
Pitcher Plant Digestion
The fluid inside a pitcher of a pitcher plant contains digestive acids and enzymes that break down the prey into nutrients that can be absorbed by the plant. Sometimes the prey slowly decomposes and survives for several days by eating the hollow interior of the pitcher. The acids and enzymes are produced by hundreds of digestive glands in the lower section of the pitcher.
The acids and enzymes eat at the soft part of insects and can even digest egg whites and meat. The exoskeletons of insects collect at the bottom of the pitcher like bones from uncollected battlefield corpses. Small insects can be digests in a few hors. A mice may take a week or more.
Species of Pitcher Plants
There are 60 different species of pitcher plants. The shape of the pitcher varies in size and shape from species to species. Some resemble beer steins. Others look like toilets. A rare species found in Borneo is called the monkey scrotum plant because, well it looks like a monkey scrotum.
The world's largest pitcher plant, the Nepethes raja, or rajah pitcher, is found in Sabah in Borneo. It is the size of a football, hold up as much as two liters of fluid, and has been known to devour animals the size of a rat. The Nepethes northiana is the largest lowland species. It is large enough to hold a liter of liquid and grab hold a child’s arm.
The fanged pitcher plant is so named because of a pair of thorn-like appendages that protrude form the bottom of the pitcher lid. The Nepethes vetchi grows on wind-blown trees It is very colorful. Some have red-and-green or red-and white stripes. Other have bright yellow or red peristomes.
A member of the water lily family, the lotus is an aquatic plant and one of the few flowering plants that bear petals and fruit at the same time. There are several types. The East Indian lotus produces pink flowers and roots that are eaten by many people in Asia. Many species bloom and whither in the summer or tropical heat. Asian lotus flowers contain a natural thermostat that kept its temperature constant.
Hans Christian von Baeyer, a professor of physics at the College of William and Mary, wrote in The Science: The lotus flower name “is actually shared by a number of different plants with blossoms of various colors, but the most celebrated in art and literature is the sacred white lotus of the Hindus: Nelumbo nucifera. Its huge, almond-shaped petals form a shallow bowl around a seedpod that is vaguely reminiscent of the nozzle of a sprinkling can. This magnificent blossom, rising on a tall stalk from a flat base of large, round leaves, is endowed with an exotic aura.” [Source: Hans Christian von Baeyer, The Sciences, January/ February 2000]
Nymphaeceae is a family of water plants which includes the water lilies, the sacred lotus (Nelumbo) and the spectacular Queen Victoria water lily (victoria amagorica). It is a family of 8 genera with 90 species found in fresh waters throughout the world. Where there are ponds, lakes and streams these plants are found. Common species in Asia include the: 1) European White Water Lily (Nymphaea alba); 2) Indian Water Lily (N. Nouchali Burmf); 3) Indian Blue Water Lily (N. Stellata Willd); 4) Barclaya longi folia Walld; 5) Pygmy Water Lily (N. tetra gona Georgi); 6) Nymphaea Stellata Willd; and 7) Sacred Lotus or Egyptian Lotus (Nelumbium speciosum Willd). The Sacred Lotus, is believed to bloom only in sunlight and the white lily, is said to bloom only with moonlight. [Source: Kyi Kyi Hla]
As food the lotus was known to the Greek Homer and was widely used by the Chinese, Japanese and Southeast Asians. Its seed may be eaten fresh or dried and used in sweet soups and deserts. The root may be used in salad, boiled in soup, or preserved in sugar and used as desert. From the root may also be extracted a fine starch used by the inhabitants of that area for certain special foods. Lotus seeds are green and resemble large peanuts and come embedded in a cup-like bulb. stalk. It is a very tasty ingredient in steamed duck or as part of the stuffing in duck roast. They can also be eaten raw. Before the era of plastics lotus leaves were used to wrap fresh fish and meat in bazaars.
Lotus, History and Culture
The lotus is featured in Asian art and is a major symbol in Buddhism and Hinduism and was showcased in ancient Egyptian architecture. It symbolizes self-development, enlightenment and purity because it is rooted in the mud, grows from through dirty water and without getting dirty and emerges as a thing of beauty. The lotus-eaters in Homer’s Odyssey was not eaters of the lotus found in Asia but rather consumed a prickly shrub with a sweet, mealy fruit found in the Mediterranean. Art and architecture in ancient Egypt was influenced by the blue lotus found there.
Hans Christian von Baeyer wrote in The Sciences: “In Buddhist tradition, lotus blossoms mark each of the seven steps in ten directions taken, paradoxically, by the newborn Buddha. But without a doubt the color of the lotus---or, more properly, its utter absence of color---a blinding whiteness that speaks of unblemished purity, underlies its magical allure.” [Source: Hans Christian von Baeyer, The Sciences, January/ February 2000]
“The lotus was the inspiration for the Phoenician capitals that preceded the Ionic order of design, the sacred flower of Hindu religions and the object of the principal mantra of Tibetan Buddhism: om mani padme hum, which means "Hail, jewel in the lotus." Given the mechanical efficiency of prayer wheels that symbolically repeat those words without pause, the lotus may be the most frequently invoked plant in the world. In various parts of the world it has been a symbol of fertility, birth, beauty, sunlight, transcendence, sexuality and the resurrection of the dead. A twelfth-century Sanskrit poem extols Brahma, "the lotus of whose navel forms thus our universe." But above all, the lotus represents purity.
What an enchanting paradox, then, that the lotus grows in muddy waters, emerging from them unblemished and untouched by pollution. An ancient Indian text refers explicitly to that wonderful quality: The white lotus, born in the water and grown in the water, rises beyond the water and remains unsoiled by the water. Thus, monks, the [Buddha], born in the world, grown up in the world, after having conquered the world, remains unsoiled by the world.
The Sacred Lotus is a large bloom on a long thick thorny and fibrous stalk. The buds are like elongated bulbs that narrow at the tip. But when the petals open the flowers are fabulous. The color of the sacred lotus is a mix of whitish pink and red. And the white lotus is pristine and pure. The fibrous stalks yield strong threads. which are used for weaving the sacred ornamental robe offered to Buddha Images.
Amid the dirty waters of small streams and rivers as well as from the semi-stagnant pools of water throughout the tropical area of Southeast Asia (Vietnam, Cambodia, Laos, Thailand, Malaysia, etc.) can be seen the bright green floating leaves and the lovely colors of the Lotus. Such is the contrast of the flower to the environment wherein it grows, that long ago, Buddha used it as a symbol of his teachings. Growing out of the impure, the dirty, and the waste products of civilization, the Lotus lifts high its stately and lovely blossom in such unsullied and pure form that it is an object lesson. [Source: The Religions of South Vietnam in Faith and Fact, US Navy, Bureau of Naval Personnel, Chaplains Division ,1967 ++]
The Lotus flower is a religious symbol as well as a popular food and a sight that creates aesthetic pleasure. There are at least five varieties of the Lotus with the water lily being included, even if not always accepted as a true Lotus; but the Thai people refer to the two types as "string Lotus" and "stalk Lotus" with several types of "string Lotus" with flowers of purple, white to pale blue, and red. There are also at least five kinds of "stalk Lotus", with each having its own characteristics and charm when closely studied. ++
Lotuses and Buddhism
Buddha taught that as the flower achieves its mark in spite of its environment, so may men lose their passions and desires and thereby find release in the spiritual serenity of Nirvana. The Lotus bud is perhaps the single most popular offering of the Buddhist as he worships at his temple, or his home altar. It is quite often held in the folded hands of the listener within the temple as sermons are given or meditation is practiced. Often in the early morning hours as the Buddhist monk makes his way through the streets with the "merit bowl" wherein the laity may earn merit by giving cooked rice, there will be a Lotus bud or two within his hand. Likewise, it has come to form a part of Asian architectural and sculptural motifs. ++
Sometimes the Lotus is compared to the feet, the heart, or the life-giving attributes of the Buddhist female. Moreover it has a history that predates Buddhism as its symbolism was also of Hindu heritage. For instance, Brahman legend tells the story of how when Brahman, the god of the universe, was creating this universe, he went to sleep on the job; as he slept, the Lotus bud appeared from his naval and its petals opened, Vishnu emerged and finished the creation. ++
Buddha used its four stages to symbolize the four types of people and their distance from enlightenment. The four stages are: (1) the Lotus bud deeply submerged as it starts its development; (2) the bud about to reach the surface of the pond; (3) after the bud has cleared the surface, but with leaf and bud still folded; and (4) the bud standing tall and straight with its beauty undefiled by the mire from which it grows. Because of this symbolism, it is always proper to use it as a floral offering to monks when ceremonies are performed or as means of earning merit. The Lotus bud signifies in Buddhism that the worshipper is capable of reaching enlightenment because of the opportunities within his grasp. The unopened bud also tends to last longer than other flowers, and it has the capacity to bloom when placed in water and left before the altar. ++
The lotus motif is a decorative feature found on the architecture of Buddhist shrines and sacred depositories such as chedis (stupas). The upper part of a chedi just below the pinnacle consists of the diamond bud—the pennant-shaped vane. The umbrella is an elongated bulbous portion of the chedi known as the banana bud. Just below it a motif of large lotus petals encircling the chedi. Next is the part of the chedi that resembles a spreading upturned lotus flower. Then comes the a motif of small lotus petals. And lastly is the motif which resembles an inverted lotus flower. These motifs add to the grace and beauty of chedis. The lotus motif also decorates the pinnacles of tiered roofs of monasteries and palaces and there is also a vessel somewhat like a fruit stand decorated with lotus petals for offering food and fruits at sacred Buddha shrines. The exotic lotus is a motif which also adorns the gold thrones on which we place Buddha images.
Lotus plants are known their ability to stay clean and dry even though they grow in mucky swamps. The surface of the lotus plant, on a microscopic level, is very rough and jagged, This repels dirty water because the contact area is reduced. Some call this phenomena the Lotus Effects. A German company called Lotusan has developed a paint inspired by the lotus plant that it claims can repel dirt just as effectively as the lotus plant.
Describing research into the lotus effect, Hans Christian von Baeyer wrote in The Sciences: “Wilhelm Barthlott of the University of Bonn in Germany spent 20 years using scanning electron microscope (SEM) survey of the micro-morphology of the skin surface of some 10 000 plants Nothing motivated Barthlott except pure scientific curiosity, and his love of plants.” [Source: Hans Christian von Baeyer, The Sciences, January/ February 2000]
The images from his work were extraordinary. “At magnifications ranging from ninety to 6,000 diameters, they portrayed an unsuspected wonderland of sculpture gardens. Most plant skins in the survey are overgrown with a forest of miniscule, wartlike protuberances, arranged in endlessly repeating patterns. Some of the protuberances look like wooden matches, with round heads on long stalks; others look like furry cones. Some of the structures are mere holes or indentations in an otherwise smooth surface, some resemble crooked hollow tubes swaying like drunken chimneys, and others are jagged shards attached at crazy angles.
Within a couple of years after his monumental summing up, Barthlott and his student Christoph Neinhuis---who later became his colleague at the university---began to notice a peculiar trend. The first step in preparing a plant surface for microscopic examination is a thorough cleaning. Although no plant in nature can escape exposure to dust and grime, some leaves, it seemed, were much easier to prepare than others. They somehow managed to keep themselves better groomed. Unexpectedly, some of the cleanest surfaces turned out to be rougher and more irregular than those of their dirtier cousins. The correlation between cleanliness and surface roughness appeared to be exactly backward. By undertaking a protracted series of microscopic observations of the interactions of leaf surfaces, dirt and water, they eventually uncovered an ingenious though strikingly simple underlying mechanism.
Imagine a leaf is a wooden board through which a forest of nails has been driven from below, so that the points stick out through the top surface. Now think of a fleck of dust magnified many times, so that it resembles a ragged piece of paper landing gently on the bed of nails. The strength of the adhesion between the paper---the dust fleck---and the board depends on the surface area of their mutual contact. Without the nails, the paper would make much better contact. A real dust fleck would stick to the flat board. But because of the pointy nails, the contact area is miniscule and the fleck is barely attached. It hovers on pointe, as it were.
Now imagine that the board is slightly tilted, and that a drop of water, magnified to the size of a great round medicine ball, rolls over the nails toward the dust fleck. (The drop of water, like the dust fleck, is only barely attracted by the nails.) Faced with the choice of balancing on the nails or clinging instead to the big, smooth surface that is rolling over it, the dust fleck quickly pops over onto the ball, sticks to it and gets carried away. Thus drops of water collect dirt from plant surfaces and roll off, leaving the rough surfaces both clean and dry.
In hundreds of experiments and detailed images, Barthlott and Neinhuis have captured and documented the phenomenon: the simple and elegant way leaves have evolved to clean themselves with rain, fog and dew. And nowhere, the investigators found, was the effect more impressive than in the lotus. The surface of the lotus leaf is covered with a dense layer of pointy little moguls [see photomicrograph below]. The botanists had stumbled upon the secret of the lotus. To celebrate their discovery, Barthlott coined the term lotus effect.
To demonstrate the phenomenon dramatically, Barthlott likes to squeeze a droplet of water-soluble liquid glue onto a lotus leaf. He smears the droplet a little with his finger, then steps back to watch. The glue quickly pulls itself back together, re-forming the droplet, and the droplet rolls off the leaf at a stately pace. Not even glue can stick to an area as small as the tip of a microscopic mogul. Just as impressive is Barthlott’s demonstration of the cleaning power of water: when a lotus leaf is covered with a dusting of fine powdered clay, and a drop of water is added, the water rolls downhill, gathering dust as it moves. In its wake is a long, clean path, like the shiny trail of a snail.
Image Sources: Wikimedia Commons
Text Sources: National Geographic, Natural History magazine, Smithsonian magazine, Wikipedia, New York Times, Washington Post, Los Angeles Times, Times of London, The Guardian, Top Secret Animal Attack Files website, The New Yorker, Time, Newsweek, Reuters, AP, AFP, The Economist, BBC, and various books and other publications.
© 2008 Jeffrey Hays
Last updated May 2014