Nelumbo nucifera, also known as Padma (Sanskrit: पद्म, romanized: Padma, lit. 'Lotus') or Kamala (Sanskrit: कमल, lit. 'Lotus'), sacred lotus, pink lotus, Indian lotus, or simply lotus, is one of two extant species of aquatic plant in the family Nelumbonaceae. It is sometimes colloquially called water lily, though this more often refers to members of the family Nymphaeaceae.Janice Glimn-Lacy, Peter B. Kaufman, Botany Illustrated: Introduction to Plants, Major Groups, Flowering Plant Families, p. 79, 2006, Springer, google books The lotus belongs in the order Proteales.
Description Lotus plants are adapted to grow in the flood plains of slow-moving rivers and delta areas. Stands of lotus drop hundreds of thousands of seeds every year to the bottom of the pond.
Some sprout immediately, though most are eaten by wildlife. The remaining seeds can remain dormant for an extensive period of time as the pond silt fills in and dries out. During flood conditions, sediments containing these seeds are broken open, and the dormant seeds rehydrate and begin a new lotus colony.
Lotus plants are cultivated in nutrient-rich, loamy, and often flooded soils, requiring warm temperatures and specific planting depths, with propagation via rhizomes, seeds, or tissue culture. It is harvested by hand or machine for stolons, flowers, seeds, and rhizomes over several months depending on climate and variety.
It is the national flower of India and unofficially of Vietnam. It has large leaves and flowers that can regulate their temperature, produces long-living seeds, and contains bioactive alkaloids. Under favourable circumstances, the seeds of this aquatic perennial may remain viable for many years, with the oldest recorded lotus germination being from seeds 1,300 years old recovered from a dry lakebed in northeastern China. Therefore, the Chinese regard the plant as a symbol of longevity.
It has a very wide native distribution, ranging from East Asia (north to the Amur region) through northern Indochina and central and northern India (at altitudes up to in the southern Himalayas),; the Russian populations have sometimes been referred to as Nelumbo komarovii, with isolated locations at the Caspian Sea. Today, the species also occurs in southern India, Sri Lanka, virtually all of Southeast Asia, New Guinea, and northern and eastern Australia, but this is probably the result of human translocations. It has a very long history ( 3,000 years) of being cultivated for its edible seeds and is commonly cultivated in water gardens. It is a highly symbolic and versatile plant used in religious offerings (especially in Hinduism and Buddhism) and diverse culinary traditions across Asia, with its flowers, seeds, and rhizomes valued for spiritual, cultural, and nutritional purposes. It holds deep cultural, spiritual, and religious significance across Hinduism, Buddhism, Jainism, Ismailism, and Chinese culture, symbolizing purity, enlightenment, spiritual awakening, and divine beauty, and is widely depicted in art, architecture, and literature.
The leaves of Nelumbo nucifera contain the flavonol miquelianin and alkaloids such as coclaurine and norcoclaurine, while the plant as a whole contains bioactive compounds including nuciferine and neferine. These constituents have been studied for their potential pharmacological effects, and the plant is used in traditional medicine and marketed as a functional food in various cultures.
Etymology The scientific name Nelumbo nucifera comes from a Sinhalese name for the plant, nelambu or nelum (නෙළඹු or නෙළුම්), and the Latin word 'nucifera', meaning "nut-bearing". Therefore, the full name translates to "nut-bearing nelumbo", referring to the plant's edible, nut-like seeds.
Classification
The lotus is often confused with the true water lilies of the genus Nymphaea, in particular N. caerulea, the "blue lotus". In fact, several older systems, such as the Bentham & Hooker system (which is widely used in the Indian subcontinent), refer to the lotus by its old synonym, Nymphaea nelumbo.
While all modern plant taxonomy systems agree that this species belongs in the genus Nelumbo, the systems disagree as to which family Nelumbo should be placed in or whether the genus should belong in its own unique family and order. According to the APG IV system, N. nucifera, N. lutea, and their extinct relatives belong in Proteales with the protea flowers due to genetic comparisons. Older systems, such as the Cronquist system, place N. nucifera and its relatives in the order Nymphaeles based on anatomical similarities. According to the APG IV classification, the closest relatives of Nelumbo include the sycamores (Platanaceae).
Botany
The lotus roots grow in pond or river bottom soil, while the leaves float on the water's surface or are held well above it. The leaf stalks (petioles) can be up to long, allowing the plant to grow in water to that depth. The peltate leaf blade or lamina can have a diameter of .Cook, Water Plants of the World (see below) loc. cit. The leaves are spaced up to apart along the rhizome, which can grow as much as in one year. The internodes are not cylindrical but swollen in the middle.
Flower The flowers are usually found on thick stems rising several centimetres above the leaves. They are showy and grow up to in diameter.
Some cultivated varieties have extraordinary numbers of petals. For example, the Chinese variety qian ban lian ("thousand petals lotus") can have between 3,000 and 4,000 petals in a single blossom and the Japanese variety ohmi myoren ("strange lotus") can have between 2,000 and 5,000 petals, the greatest number recorded for any species of plant.
Lotus flowers regulate their temperature to within a narrow range, maintaining temperatures of , even with air temperatures as low as . Researchers think that this may be to attract cold-blooded insect pollinators to the flowers. Nelumbo nucifera is not closely related to other plants known to be thermogenic.
Seed A fertilized lotus flower bears fruit that contains a cluster of 10 to 30 seeds. Each seed is ovoid 1–2.5 cm wide by 1–1.5 cm long with a brownish coat. Lotus seeds can remain viable after long periods of dormancy. In 1994, a seed from a sacred lotus, dated at roughly 1,300 years old ± 270 years, was successfully germinated.
The genome of the sacred lotus was sequenced in May 2013. A dedicated genome database lists additional genome assemblies sequenced since then.
Cultivation The sacred lotus grows in water about to deep. In colder climates, a deeper water level protects the tubers more effectively, and improves growth and flowering. The sacred lotus germinates at temperatures above . Most varieties are not naturally cold-hardy, but may readily adapt to living outdoors year-round in USDA hardiness zones 6 through 11 (with some growers having success in zones as low as 4 or 5); the higher the zone's number, the greater the adaptability of the plants. In the growing season (from April to September in the northern hemisphere), the average daytime temperature needed is . In regions with low light levels in winter, the sacred lotus has a period of dormancy. The tubers are not cold-resistant if removed from water and exposed to the air; but when kept underwater in soil, the energy-rich tubers can overwinter temperatures below . If the plants are taken out of the water for wintertime storage (mostly in exceptionally cold climates), the tubers and roots must be stored in a stable, frost-free location, such as a garage, preferably in a cardboard box or container filled completely with vermiculite or perlite. Care must be taken to fully insulate the tubers.
Planting The sacred lotus requires a nutrient-rich and loam soil. In the beginning of the summer period (from March until May in the northern hemisphere), a small part of rhizome with at least one eye is either planted in ponds or directly into a flooded field. It can also be propagated via seeds or buds. Furthermore, tissue culture is a promising propagation method for the future to produce high volumes of uniform, true-to-type, disease-free materials.
The first step of cultivation is to plough the dry field. One round of manure is applied after ten days, before flooding the field. To support a quick initial growth, the water level is relatively low and increases when plants grow. Then a maximum of approximately with grid spacing of are used to plant directly into the mud below the soil surface.
Harvest
The stolon is ready to harvest two to three months after planting. It must be harvested before flowering. Harvesting the stolon is done by manual labor. For this step, the field is not drained. The stolon is pulled out of the water by pulling and shaking the young leaves in the shallow water.
The first leaves and flowers can be harvested three months after planting. Flowers can be picked every two days during summer and every three days during the colder season. Four months after planting, the production of flowers has its climax. The harvest of flowers is usually done by hand for three to four months.
Seeds and seed pods can be harvested when they turn black four to eight months after planting. After sun drying for two to three days, they are processed by mechanical tools to separate seed coats and embryos.
The rhizomes mature to a suitable stage for eating in approximately six to nine months. Early varieties are harvested in July until September and late varieties from October until March, after the ponds or fields are drained. The large, starch-rich rhizomes are easy to dig out of the drained soil. In small-scale production, they are harvested by hand using fork-like tools. In Japan and on bigger farms, manual labour harvesting is fully replaced by machines.
Varieties and cultivars Lotus varieties have been classified according to their use into three types: rhizome lotus, seed lotus, and flower lotus. Varieties that show more than one of these characteristics are classified by the strongest feature. Regarding production area in China, rhizome lotus has the largest area with , followed by seed lotus with .
Rhizome lotus Rhizome lotus cultivars produce a higher yield and higher quality rhizomes than seed or flower lotus cultivars. Furthermore, this group grows tall and produces few to no flowers.
Cultivars can be classified by harvest time or by the depth of rhizomes into these types: Pre-mature (early) cultivars are harvested before the end of July, serotinous (late) cultivars from September on, and mid-serotinous or mid-matutinal cultivars are in between these harvest times. Using pre-mature cultivars, rhizomes can be harvested earlier and sold for a higher price. Adlittoral (shallow), deep, and intermediate cultivars are distinguished according to the depth in which the rhizomes grow underground. Adlittoral cultivars range from depth and are often premature. They develop faster due to higher temperatures in surface soil layers. When harvested in July, adlittorals have higher yields than deeper-growing cultivars, but not necessarily when harvested in September. Rhizomes of adlittoral cultivars are crisp and good for frying purposes. Deep cultivars grow more than deep. They are often serotinous and can harvest high yields. Their rhizomes are starch-rich. The main popular Nelumbo nucifera cultivars in China are Elian 1, Elian 4, Elian 5, 9217, Xin 1, and 00–01. The average yield of these cultivars is 7.5–15 t/ha (3.3–6.7 tons/acre) of harvest in July and 30–45 t/ha (13–20 tons/acre) of harvest in September. In Australia, the cultivar grown for the fresh rhizome market in Guangdong and Japan, the common rhizome cultivars are Tenno and Bitchu.
Seed lotus