Plant 262

Nelumbo nucifera Gaertn. (Nelumbonaceae)

Sacred lotus

Nelumbo nucifera is not only beautiful but is a very useful and remarkable plant. All parts are edible, the tubers and seeds being principally consumed; several parts have medicinal uses and are a good source of certain vitamins and minerals. The plant has religious significance in Hinduism and Buddhism. It is the national flower of India and Vietnam. The sacred lotus has been a domesticated crop in Asia for several thousand years. It makes an impressive garden ornamental and, for centuries, it has been represented in Chinese and Japanese art.

Nelumbo nucifera, with pink or white flowers, has a wide distribution in Asia. A closely related species, Nelumbo komarovii, grows in far eastern Russia and a third species is the North American Nelumbo lutea. Lotus grows as large perennial herbs in shallow ponds or other bodies of water, often forming huge colonies. The production of branched underground rhizomes, full of elongated air chambers, allows the plant to spread. The large, round leaves are borne on long leaf stalks, and can be floating but are generally emergent. The flowers with numerous petals are solitary and held above the water surface by long stalks. The fruits are indehiscent nuts and these are found in cavities within the receptacle (a top-shaped upper part of the flower stalk). The receptacles in their dried state make attractive floral decorations.

Buds open slightly on the first day of flowering allowing entry to pollinating insects, largely beetles, which are trapped inside overnight. Flowers, which can be up to 20 cm in diameter, open much more widely on the second day exposing pollen-bearing anthers. The temperature of the petals increases before opening and the heat inside the flower can be up to 36 degrees Celsius at night, even if the ambient temperature falls much lower. Theories suggest this may help the beetles to maintain warmth in order to stay active during the night and to fly when released.

Remarkably, fruits of Nelumbo nucifera found in a dry lakebed in northeastern China, carbon-dated to about 1,300 years old, were found to be viable and germinated. These are perhaps the longest living fruits in the world.

Studies of sacred lotus leaf surfaces show that they are covered in tightly packed papillae, which produce epicuticular wax, and this gives the leaves super water repellence. The surfaces are self-cleaning. The manufacture of a self-cleaning industrial paint has been modelled on this effect.

Further reading

Griffiths M 2009. The lotus quest. In search of the sacred flower. St. Martin's Press.

Seymour RS and Schultze-Motel P 1998. Physiological temperature regulation by flowers of the sacred lotus. Philosophical Transactions: Biological Sciences 353: 935-943.

Shen-Miller J et al. 2002. Long-living lotus: germination and soil gamma-irradiation of centuries-old fruits, and cultivation, growth, and phenotypic abnormalities of offspring. American Journal of Botany 89: 236-247.

Serena Marner