Nelumbo nucifera

• 1. Introduction

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  Nelumbo nucifera, the sacred lotus, once grew a living plant from a seed about 1,300 years old, give or take 270 years. Researchers germinated that seed in 1994. Seeds of similar age have been recovered from a dry lakebed in northeastern China, and that is one reason the Chinese regard the plant as a symbol of longevity. How does an aquatic plant keep a seed alive for so long? Why do botanists still disagree about which family it belongs to? How did a single flower become sacred in several faiths, a national emblem, and a model for engineers? The answers begin in the water.

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• 2. Names and Family Tree

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  Padma and Kamala are two Sanskrit words that both mean simply lotus. Sacred lotus, pink lotus and Indian lotus are other names for the same species. The scientific name has a different origin. Nelumbo comes from nelambu or nelum, a Sinhalese name for the plant. Nucifera is Latin for nut-bearing, a nod to the edible, nut-like seeds. Together the name means nut-bearing nelumbo.

  Many people call the lotus a water lily, but that label more often belongs to the family Nymphaeaceae. The true water lily Nymphaea caerulea, known as the blue lotus, adds to the muddle. Some older systems, such as the Bentham and Hooker system widely used in the Indian subcontinent, even file the lotus under the old synonym Nymphaea nelumbo.

  Modern taxonomists agree on the genus but not on its placement. The APG IV system uses genetic comparisons to put N. nucifera, N. lutea and their extinct relatives in the order Proteales, alongside the protea flowers. On that evidence the closest relatives of Nelumbo include the sycamores of the family Platanaceae. The older Cronquist system leaned on anatomical similarities and chose the order Nymphaeles instead. The family Nelumbonaceae holds only two living species, and the sacred lotus can be crossed with the yellow lotus to produce hybrids.

  Whatever its filing, the plant is easiest to recognize in a pond, where its leaves can stand well above the surface.

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• 3. Architecture of a Pond Giant

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  A single lotus leaf blade can measure 80 to 100 centimetres across. It rides on a stalk, called a petiole, that can reach 200 centimetres, which lets the plant grow in water that deep. The roots anchor in the bottom soil of a pond or river, while the leaves either float or are held high. Leaves sit up to 2 metres apart along the rhizome, and that underground stem can lengthen by as much as 20 metres in a single year.

  The flowers rise on thick stems a few centimetres above the foliage. They are showy and can grow up to 35 centimetres wide. Some cultivated varieties carry astonishing numbers of petals. The Chinese variety qian ban lian, meaning thousand petals lotus, can have between 3,000 and 4,000 petals in one blossom. The Japanese variety ohmi myoren, meaning strange lotus, can have between 2,000 and 5,000, the greatest number recorded for any plant species.

  A lotus blossom also keeps itself warm. It holds its temperature between 30 and 35 degrees Celsius even when the surrounding air is only 10 degrees. Researchers think this may attract cold-blooded insect pollinators. The sacred lotus is not closely related to the other plants known to generate heat this way.

  The natural range of the species is vast. It runs from central and northern India, at altitudes up to 1400 metres in the southern Himalayas, through northern Indochina and East Asia as far north as the Amur region. Russian populations have sometimes been called Nelumbo komarovii, and isolated stands exist at the Caspian Sea. Today the plant also grows in southern India, Sri Lanka, nearly all of Southeast Asia, New Guinea, and northern and eastern Australia. Much of that spread is probably the work of people moving it around. People have cultivated it for its edible seeds for about 3,000 years.

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• 4. Seeds That Wait

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  Each year a stand of lotus lets hundreds of thousands of seeds fall to the bottom of its pond. Wildlife eats most of them. A few sprout at once. The rest can lie dormant for a long time while the pond silts in and dries out. When floods arrive, the sediments holding the seeds are broken open. The dormant seeds then rehydrate and start a new lotus colony.

  A fertilized flower produces a fruit holding a cluster of 10 to 30 seeds. Every seed is egg-shaped and has a brownish coat. A seed measures 1 to 2.5 centimetres across and 1 to 1.5 centimetres long.

  In May 2013 scientists finished sequencing the genome of the sacred lotus. A dedicated genome database now lists further assemblies produced since then.

  The seeds also hold thermal-stable proteins that appear tied to their long life, protecting and repairing cells under stress. Researchers see these proteins as possible tools for protein bioengineering.

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• 5. Farming the Lotus

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  In China, rhizome lotus covers about 200000 hectares, far more than the 20000 hectares given to seed lotus. Growers sort varieties into three types by use: rhizome, seed and flower. A variety that shows more than one trait is classified by its strongest feature.

  Rhizome cultivars give the best yield and quality of underground stems. They grow tall and bear few flowers or none. Early cultivars are harvested before the end of July and sell at a higher price, while late ones come in from September onward. Shallow cultivars grow their rhizomes 10 to 20 centimetres down, warm up faster, and give crisp rhizomes that suit frying. Deep cultivars grow below 40 centimetres and give starch-rich rhizomes. Popular Chinese cultivars include Elian 1, Elian 4 and Elian 5. In Australia, growers supplying fresh rhizome markets in Guangdong and Japan use Tenno and Bitchu.

  Seed cultivars have many carpels and large seeds, but thin, fibrous roots that form poor rhizomes. Cunsanlian, Xianglian 1 and Ganlian 62 are among the popular Chinese choices. Flower cultivars are purely ornamental, with the shortest plants and the most blooms. Their petals come in white, yellow, pink and red, or in two colours such as white with pink tips. Wanlian, the bowl lotus, is a miniature type that blooms longer than other lotuses.

  Planting begins with a small piece of rhizome that has at least one eye, set into a pond or a flooded field. The soil must be rich and loamy. Seeds, buds and tissue culture also work, and tissue culture is a promising route to large volumes of uniform, disease-free plants. A farmer ploughs the dry field first and spreads manure ten days later, before flooding.

  The stolon is ready two to three months after planting and must be pulled before flowering. Workers pull it from the undrained field by shaking the young leaves. Flowers can be picked every two days in summer and every three days in cooler weather, with peak production four months after planting. Seed pods are cut when they turn black, four to eight months in, then dried in the sun for two to three days. Rhizomes mature in six to nine months, after the field is drained. In Japan and on large farms, machines have fully replaced hand digging.

  About 70 percent of the lotus grown for people to eat comes from China, where the planted area was estimated at 300000 hectares in 2005. One common system rotates lotus with rice and vegetables. Rhizomes come out in July, rice follows and is harvested in October, and cabbage or spinach can fill the field from November until March. Another system raises fish, shrimp or crab in the same flooded field, which uses the water more efficiently.

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• 6. From Root to Plate

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  In Japan, lotus rhizome makes up about 1 percent of all vegetables eaten. The country grows its own but still imports 18,000 tons each year, and China supplies 15,000 of them. The rhizome is a classic banquet dish across China, Japan, India and Pakistan. Cooks deep-fry it, stir-fry it, or stuff it with meats or preserved fruits. They also simmer it in soups, soak it in syrup, or pickle it in vinegar with sugar, chili and garlic. Its crunch and its starch give a texture close to raw potato.

  Regional cooking varies widely. In Sri Lanka the root is often simmered in coconut milk gravy. In India it becomes a dry curry called kamala kakaṛī sabzî. Korea drinks lotus root tea. Fresh slices brown quickly once cut.

  Seeds are shaped into moon cake fillings, noodles, paste, rice wine, ice cream and phool makhana popcorn. Fresh seeds spoil easily, especially from fungal infection, so dried seeds dominate markets. Traditional sun baking with charcoal loses nutrients, while freeze-drying keeps them and the flavour survives rehydration.

  Young stems turn up in a Vietnamese salad and in Thai dishes such as keang som sai bua, a sour soup. In Kerala and Tamil Nadu, stem slices are salted, dried and fried as thamara vathal. In the Philippines, an indigenous variety called tukal is cooked in coconut milk.

  Leaves wrap zongzi and lo mai gai in Chinese cooking, and kao hor bai bua, a fried rice, in Thailand. Vietnamese cooks wrap cốm, young green rice, in lotus leaves, which give it a distinctive scent. Vietnamese tea makers perfume tea leaves with lotus stamens, producing trà sen. Korea makes tea from dried white lotus petals.

  Eating the petals, leaves or rhizome raw carries a risk of parasite transmission, including Fasciolopsis buski, so cooking is recommended. Fresh rhizomes also keep poorly, which limits exports. Stacked rhizomes stay fresh for about three weeks. Layers of silver sand and soil stretch that to two months for home use. A salt solution dip allows up to five months of storage, though it is costly and hard to wash off before eating.

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• 7. Medicine, Cleanup and Cloth

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  The Shen Nong's Herbal Classic, written as early as the Han Dynasty, recorded lotus seeds as sweet and astringent and as nourishing to the heart and kidney. Rhizomes, leaves and seeds have long featured in folk medicine, Ayurveda and Chinese medicine, where the seed embryo is still used as lian zi xin. China's Ministry of Health approved the plant as both food and medicine. The town of Jianning calls itself the town of Jianlian lotus seeds, and Guangchang claims the white lotus seed.

  Numbers from the laboratory back up the nutrition claims. A 100-gram serving of root provides about 74 calories and 44 milligrams of vitamin C, or 73 percent of the daily recommended value. Seeds are rich in high-quality protein, with albumin making up 42 percent and globulin 27 percent. The leaves contain miquelianin, coclaurine and norcoclaurine, and the plant holds nuciferine and neferine, all studied for possible pharmacological effects.

  The lotus also cleans water. Its floating leaves block sunlight from the lower water, which suppresses algae and leaves oxygen up to 20 percent higher than in other aquatic plant systems. It takes up more phosphorus than water hyacinth, a plant already used for remediation. Through rhizofiltration, it removed 96 percent of copper and 85 percent of cadmium after a seven-day incubation. The effect on rhizome quality for eating still needs study.

  The waxy surface of its leaves repels water, and engineers borrowed the idea as the lotus effect in materials that resist water and clean themselves. Researchers at the National University of Singapore drew on that structure to develop eAir, an aero-elastic sensor that detects subtle pressure changes. Dried seed heads, shaped like watering can spouts, are sold worldwide for flower arranging.

  Lotus silk is made from the plant's fibres at only two places, Inle Lake in Myanmar and Siem Reap in Cambodia. Weavers use the thread for kya thingan, the lotus robes placed on Buddha images.

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• 8. A Flower of Many Faiths

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  Hindu temples offer lotus flowers to most female deities, above all Lakshmi. Among male deities, Vishnu receives lotuses for prosperity and Shiva for salvation. Worshippers drape deities in lotus garlands, use petals in puja, and string the seeds into prayer beads. Most Buddhist temples offer lotuses to the Buddha, and the flower also appears in the Hindu wedding garland called Varamala.

  Hindu iconography is full of the flower. Lakshmi sits or stands on a lotus and holds lotuses in two of her four hands. Vishnu is always shown with a lotus in one hand, and the epithet Kamalanayana, lotus-eyed, praises his eyes. The plant's life in murky water stands for a choice between comfortable darkness and a dharmic life lived toward the light. Its roots in mud suggest the cycle of life and death, and its bloom suggests moksha. Tantra uses the thousand-petalled lotus Sahasrara, and yoga uses Padmasana, the lotus pose.

  The Mahabharata describes a battle formation shaped like a blooming lotus, the Padmavyuha, used in the 18-day Kurukshethra war. Indian architects built domes like lotus buds, pillars like stalks and arches like inverted lotuses. The lotus throne, a stylized flower used as a seat for a figure, spread from India to East Asia and appears in Buddhist, Hindu and Jain art.

  In Persia, where it is called Nilufar Abi, the lotus appears in reliefs of the Achaemenid period from 552 BC, including the statue of Anahita at Persepolis. It was part of Kaveh the blacksmith's banner and later the flag of the Sasanian Empire. Today it is the symbol of the Iranian Solar Hijri calendar. The Bible also mentions the flower. In South Asian Ismaili literature, one poem compares the lotus to a pure soul that stays unstained in murky water and is nourished by true knowledge, which only the true guide can give.

  The lotus is the national flower of India, and the Bharatiya Janata Party uses it as its party symbol. The party once flew lotuses in pink, white, blue, red and saffron. It now mostly uses a black-and-white logo, because Electronic Voting Machines in India accept only black-and-white logos. Vietnam has no official national flower, yet almost every modern Vietnamese government, communist or not, has used lotus imagery. Advocates want the government to make the lotus official, citing straw polls that show very high approval among Vietnamese citizens.

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