1408

3: Dye and tannin-producing plants

Lawsonia inermis L.

Sp. Pl. 1: 349 (1753).

LYTHRACEAE

2n = 30

Lawsonia spinosa L. (1753), Lawsonia alba Lamk (1789).

Henna, Egyptian privet, camphire (En). Henné (Fr). Indonesia: inai (general), pacar kuku (Javanese). Malaysia: pacar kuku, inai, hinna. Philippines: cinamomo (Tagalog). Burma: dan. Cambodia: krâpéén. Laos: kaaw. Thailand: thian khaao, thian daeng, thian king. Vietnam: lá mòn, nhuôm móng tay.

Henna occurs wild from Iran to western India. From there it has been spread eastward to the rest of India and Indonesia, and westward to the Middle East where it became one of the important plants of Islam. It later followed Islamic armies and traders from Arabia reaching as far as Spain, Madagascar, the Moluccas, Indo-China and Japan. It is now distributed throughout the tropics and subtropics. Henna is mostly grown in home gardens and commercial production is limited to a few places in India, Pakistan, Egypt, Libya, and the Sudan.

Henna is one of the oldest cosmetics in the world and its leaves are used to colour the fingernails, to paint or decorate the palms of the hands and the soles of the feet, and to dye the hair. Written records of its use date back more than 2500 years. It is of great importance in Islam, where it is used in many ceremonies, especially marriage. This latter use has been adopted also in Hinduism. Henna is also used as a perfume.
Throughout South-East Asia and Indo-China up to Japan it is mainly used by women as a dye for the fingernails. In other areas this is only a secondary use. The use of henna to dye the palms of the hands and the soles of the feet has spread through most of the Muslim world and India. As part of the preparations for the marriage ceremony, the hands and feet of the bride are often very elaborately decorated. Henna is used universally as a basis for hair dyes. A wide range of shades from shining, reddish-blond to chestnut brown and intense, deep black can be obtained by the use of admixtures or by combining the treatment with other ones. Indigo is commonly added to obtain a black colour. This use of henna is not restricted to women. In Iran and Afghanistan men often use it to dye their hair and beards. It is even used to dye the manes and tails of horses of dignitaries for grand parades.
To prepare the dye for skin, nails or hair, fresh or dried leaves or henna powder are rubbed with water to which some lemon juice and lime are added to obtain a paste. Depending on the use, the colour required, and the locality, substances like gambier, powder of areca nut, indigo or alum may be added. The paste is carefully applied to the skin or nails, or rubbed into the hair and left for 6—12 hours, covered with a damp cloth or sometimes a betel leaf. The colour is fast and cannot be removed by washing; it has to wear off.
In the past, henna was widely used to dye silk and wool, and less commonly cotton. It may still be used in the dyeing of Morocco leather.
The use of a perfume made from the flowers of henna is largely restricted to Egypt, northern India and Java. The perfume is greenish in colour and is prepared by macerating the flowers in oil.
Henna is widely grown in gardens as an ornamental or as a hedge plant, appreciated for the strong, pleasant fragrance of its flowers, which is reminiscent of tea rose (Rosa chinensis Jacq.).
The wood of henna is fine grained and hard and has been used to make tent pegs and tool handles in India. Small twigs are used as toothbrushes in Indonesia.
In traditional medicine henna is used as a panacea against almost any disease. Only the medicinal uses that have been confirmed in clinical tests are mentioned here. Extracts of the leaves have an astringent effect on the skin, making it somewhat hydrophobic. This effect, combined with a slight bactericidal and fungicidal action, makes it a useful medicine against many skin and nail complaints. In Arabic and Ayurvedic medicine, preparations from the leaves and possibly other parts of the plant are used in childbirth and as an abortifacient. Leaves and roots are effective against certain forms of diarrhoea.

Because large quantities of henna are produced at home or for the local market, and because henna is mostly classified under categories including several other products, it is impossible to obtain accurate estimates of production. Exports of powdered and dried leaves from India, Egypt and the Sudan amounted to 6000—8000 t/year in the period 1975—1980. Total exports must be over 10 000 t/year. Demand for henna rose rapidly between 1960 and 1980, but has since levelled off. The main importers are the Arab countries, France, Britain and the United States.

The dyeing agent in henna is lawsone or 2-hydroxy-1,4-naphthaquinone (naphthalenedione) (C₁₀H₄O₃), which is present in the leaves at a concentration of 1—1.5(—2)%. It attaches itself strongly to proteins, and as a result the dye is very fast. The stems contain variable amounts of tannins. On steam distillation, the flowers yield 0.01—0.02% essential oils, which can be used as a basis for perfumes. These oils mainly consist of a- and ß-ionones. The seeds contain about 10% of a non-drying, viscous oil, composed mainly of oleic, linoleic and stearic acids.

A much-branched, glabrous shrub or small tree, 2—6 m tall, with greyish-brown bark, unarmed when young, older plants with spine-tipped branchlets. Young branches quadrangular. Leaves opposite, entire and subsessile, elliptic to broadly lanceolate, 1.5—5 cm x 0.5—2 cm, acuminate. Flowers numerous in large, pyramidal, terminal cymes, fragrant, 1 cm across and 4-merous, calyx with 2 mm long tube, and 3 mm long spreading lobes; petals orbicular or obovate, white or red; stamens 8, inserted in pairs on the rim of the calyx tube; ovary 4-celled, style up to 5 mm long, erect. Fruit a globose capsule, 4—8 mm in diameter, many-seeded, opening irregularly. Seeds 3 mm across, angular, with thick seed-coat.

Henna can grow to the size of a large shrub or even small tree, but is normally grown like lucerne (Medicago sativa L.), i.e. as a short-lived perennial crop, up to 60—70 cm tall.

Red and white-flowered types are sometimes distinguished as different botanical varieties. Plants with red flowers are much less common than plants with white ones.

Henna requires high temperatures for germination, growth and development. It is adapted to a wide range of conditions. It tolerates poor, stony and sandy soils, but is also well adapted to heavy, fertile clay soils. Low air humidity and drought are tolerated.

When grown commercially, henna is either grown from seed and transplanted, or propagated by cuttings. In northern Africa land is prepared carefully by ploughing up to 40 cm deep, and heavily manuring. Fields are then levelled and prepared for basin irrigation. In India, where production is less intensive, land is only ploughed a few times.
Because of its hard seed-coat, henna seeds have to be pre-germinated before sowing. They are first steeped in water for 3—7 days, during which time the water is changed daily. They are then placed in small heaps and kept moist and warm for a few days. Care is taken to drain excess water. When the seed-coat has softened and the seed has started to swell, it is ready to be sown in a nursery. During the first days after sowing, the soil should be kept moist and daily irrigations are often required. When the plants are about 40 cm tall they are lifted, cut back to about 15 cm and transplanted. Planting densities range widely from 20 000 to 200 000 plants/ha, depending on water availability. An amount of 3—5 kg of seed per ha is needed. For propagation by cuttings, branches with 6—8 buds are used.

Under intensive commercial production, as in northern Africa, the crop is irrigated during the dry season and heavily fertilized. In India it is grown on a larger scale, less intensively, often without irrigation and rarely fertilized. Fields are hoed once or twice per year and weeded when required. Plants produce their maximum yields during the first 4—8 years after planting, but are often left in the field for 12—25(—40) years. Henna removes large quantities of nutrients from the soil. A yield of 1000 kg dry leaves removes 180—190 kg N, 100—150 kg K₂O and 10—30 kg P₂O₅.

Very few pests and diseases attack henna. A black root rot caused by Corticium koleroga and a bacterial leaf-spot caused by Xanthomonas lawsoniae, have been reported from western India.

Plants are generally harvested twice a year from the second year onwards under intensive cultivation. Harvesting starts 1 or 2 years later under extensive management. During the first year plants are cut at about 5 cm above the ground, later they are cut at ground level. Harvesting is done when the flower buds start to form.

Few reliable statistics on yields are available. Under irrigation, henna may yield 2500—3000 kg/ha per year of leaves on dry weight basis, reaching 4000 kg/ha under optimal conditions. Under rainfed conditions in northern India yields of 700—1500 kg/ha are obtained.

In South-East Asia fresh leaves are picked from the home garden when needed and used fresh. In the Arab world and India, leafy branches are harvested, left to dry, and the leaves are separated from the branches by beating; the dry sticks may be left around the field as fencing. Drying should be rapid to retain the green colour of the leaves, which is an indication of good quality. Because of the better drying conditions, leaves harvested during the hot dry season are of better quality than those from the second harvest. For export, dried leaves are packed into bales of 170 kg. Alternatively, the dried leaves are milled to powder. Dried leaves are preferred by most traders, as they are less easily adulterated.

A large number of traditional cultivars exists, often associated with the location of production, differing in size of the leaves or in colour of the flowers. No inventory of the variation has been made.

The very low toxicity of henna and its strong roots in tradition make it one of the few natural dyes for which demand is still growing. The ongoing research for innocuous natural dyes may add to its present uses. If more attention were given to the selection of cultivars with a high lawsone content and to the development of better drying and processing techniques, it should be possible to expand its commercial production to more humid areas.

Aubaile-Sallenave, F., 1982. Les voyages du henné. Journal d'Agriculture Traditionelle et de Botanique Appliquée 29: 123—178.
Kolarkar, A.S., Singh, N. & Shankarnarayanan, K.A., 1981. Note on Mehendi (Lawsonia inermis L.) cultivation in normal and degraded lands of western Rajastan. Indian Journal of Soil Conservation 9: 71—74.
Lemordant, D. & Forestier, J.P., 1983. Usages médicinaux traditionels et propriétés pharmacologiques de Lawsonia inermis L., Lythracées. Journal d'Agriculture Traditionelle et de Botanique Appliquée 30: 69—89.
Lemordant, D. & Forestier, J.P., 1983. Commerce et henné. Identification, contrôle, fraudes, additifs. Journal d'Agriculture Traditionelle et de Botanique Appliquée 30: 283—310.
Sastri, B.N. (Editor), 1962. The wealth of India. Raw materials. Vol. 6. Council of Scientific and Industrial Research, New Delhi. pp. 47—50.
Scarone, F., 1939. Le henné dans le monde Musulman. L'Agronomie coloniale 28: 97—107, 129—140.

L.P.A. Oyen

Oyen, L.P.A., 1991. Lawsonia inermis L.. In: Lemmens, R.H.M.J. and Wulijarni-Soetjipto, N. (Editors): Plant Resources of South-East Asia No 3: Dye and tannin-producing plants. PROSEA Foundation, Bogor, Indonesia. Database record: prota4u.org/prosea