Urena lobata (PROTA)
|Geographic coverage Africa|
|Geographic coverage World|
|Carbohydrate / starch|
|Dye / tannin|
|Forage / feed|
Urena lobata L.
- Protologue: Sp. pl. 2: 692 (1753).
- Family: Malvaceae
- Chromosome number: 2n = 28, 56
- Congo jute, aramina, bur-mallow, cadillo, caesar weed, hibiscus bur, urena (En).
- Jute du Congo, jute de Madagascar, uréna, goune de Madagascar, herbe à paniers, grand cousin (Fr).
- Aguaxima, carrapicho do mato, carrapicho de lavadeira, carrapicho redondo, guaxima rósea, malvaísco, malva de embira, malva roxa, malva rósea (Po).
- Mpuruza, mchokochole jike, mtakawa jike (Sw).
Origin and geographic distribution
The origin of Urena lobata is not certain, but it is probably of African or Asian origin. It is now widely distributed in a wild or naturalised state throughout the tropics and subtropics. In tropical Africa it occurs naturally from Cape Verde and Senegal eastward to Ethiopia and Eritrea, and southward across the continent to South Africa. It also occurs in the Indian Ocean islands. Urena lobata is grown as a commercial fibre crop in DR Congo, and for local use in Ghana, Nigeria and elsewhere in tropical Africa; commercial fibre production in Angola and Madagascar is mainly based on wild or naturalized plants.
The bast fibre from Urena lobata is widely used traditionally for making cordage and coarse textiles, and industrially as a substitute for jute (Corchorus spp.), for instance to make sacks, carpets, cordage and upholstery. It is often used mixed with jute. In tropical Africa and elsewhere Urena lobata serves for making string, twines, ropes, fishing lines and nets, and nets for hunting, while the unprocessed bark is often used as tying material. In Ghana the stripped and plaited bark is used to bind loads. In Gabon it is used to affix leaves for thatching. In Malawi the stems are woven into walls of grain stores. In Madagascar the fibre is locally used in the manufacture of bags. The fibre of Urena lobata can be made into strong, bank-note quality paper and whole plants can be pulped as well.
Young shoots and leaves are eaten as a vegetable. In Malawi the flowers are eaten as a side-dish. The seeds contain oil and are mucilaginous and they are boiled in soups and with cereals. Cooked with rice they give it a pleasant slipperiness. Domestic animals eat the foliage. Some selections are grown as ornamental pot plants, flowering in winter.
The medicinal uses of Urena lobata are widespread and numerous, also in tropical Africa. It is considered expectorant and emollient. In Côte d’Ivoire a decoction of the plant is taken as oxytocic and against fever, in the Central African Republic against pneumonia. In Nigeria a preparation of the root is applied externally against rheumatism, a purpose for which it is also used e.g. in Vietnam. In Zanzibar and Indonesia a decoction of the root is taken against indigestion. In Madagascar a preparation of the root is applied to treat infected eyelids and against syphilis. Scrapings of the stem bark are put on wounds. In Gabon a macerate of the stem bark or root is prescribed against diarrhoea. In Madagascar a decoction of bark and root is given to children with enteritis or stomach pain. The leaves are widely used to induce labour or facilitate childbirth. In Côte d’Ivoire a preparation of the leaves with those of other plants is applied to treat menstrual problems. In Togo woman drink a decoction of the leaves and sometimes also from the stems and leaves of Vernonia cinerea (L.) Less. against infertility. In Benin a maceration of the leaves is taken against infectious diarrhoea. In Congo sap expressed from the leaves is given to women giving birth to their first child, and a leaf decoction is drunk against hypertension. In DR Congo powdered leaves with powdered clay in water is taken regularly as a treatment of asthma. In Uganda leaves are used against snake-bites and a leaf infusion is taken against diarrhoea. In Madagascar sap from the leaves is dripped onto wounds and a poultice of boiled leaves is applied to rheumatic inflammations, while a poultice of leaves and seeds is applied against problems of the gall bladder and other intestinal complaints. In Guinea water in which flowers are steeped is drunk as antiseptic. In Madagascar a decoction of the flowers is taken against respiratory problems.
Production and international trade
As a traditional fibre crop Urena lobata is grown in many parts of the tropics, including tropical Africa. It was tested as a commercial crop, for instance in DR Congo, Nigeria and Sierra Leone. An extensive research programme was started in DR Congo in 1929, which led to large-scale production around the 1950s. After the 1970s production declined dramatically mainly due to competition from synthetic fibres and jute. Recent production and trade statistics of the fibre are not available, partly as they are often grouped together with those of jute. In the 1970s world production was estimated at 38,000 t per year, with about 70% produced in Brazil, 20% in DR Congo, and smaller amounts in Madagascar, Angola and Peru. Production in DR Congo in 1991 was estimated at 4300 t/year.
Fresh stems of Urena lobata yield (3–)5–6(–7)% retted bast fibre. The fibre is fine, soft, flexible and lustrous, with a creamy white or pale yellow colour. It resembles jute more than other jute substitutes, such as kenaf (Hibiscus cannabinus L.) and roselle (Hibiscus sabdariffa L.). It can be spun on jute machinery without any change to the machines and without the operators needing experience with Urena lobata. The bast fibre cells are (0.8–)1.4–4.5(–5.9) mm long, with a diameter of (9–)12–19(–34) μm. Fibres investigated in Nigeria were on average 2.5 mm long and 21.6 μm wide, with a lumen width of 10.9 μm. Information on the fibre composition shows a wide variation in cellulose (63–87%) and lignin (7–12%) contents. Fibre strands extracted from wild plants are usually only about 1 m long, whereas fibre strands from cultivated plants has an average length of about 2 m. Rope made of Urena lobata fibre is considered less suitable for wet conditions, because of the lower wet strength and the fact that it deteriorates rapidly. The fibre quality can be improved by chemically joining them with acrylonitrile fibres. Kraft pulping experiments with Urena lobata bark and pith in South Africa gave pulp yields of 43–47%.
Per 100 g edible portion the raw leaves contain: water 81.8 g, energy 226 kJ (54 kcal), protein 3.2 g, fat 0.1 g, total carbohydrate (including fibre) 12.8 g, fibre 1.8 g, P 67 mg (Leung, Busson & Jardin, 1968). The composition of Urena lobata forage (moisture content 79.4%) in southern Nigeria was on a dry matter basis: crude protein 15.3%, ether extract 2.0%, crude fibre 17.6%, ash 6.0%, silica 3.9%, N-free extract 59.1%.
The seeds contain 7–18% oil, with linoleic acid, palmitic acid and oleic acid as major fatty acids, but also containing other poly-unsaturated fatty acids and the cyclopropenoid acids malvalic acid and sterculic acid. However, concentrations of the different compounds vary widely.
The numerous medicinal uses of Urena lobata are reflected by numerous biologically active compounds. The aerial parts contain the flavonoids quercetin, kaempferol, rutin, afzelin, astragalin, tiliroside, crenuloside and several kaempferol glycosides. They further contain the phenolic compounds syringic acid, glucosyringic acid, salicylic acid, protocatechuic acid, caffeic acid, diisobutyl phthalate, and also maleic acid and several long-chain fatty acids with an uneven number of C-atoms. A methanolic extract of Urena lobata roots has shown antibacterial activity against a range of microorganisms. Imperatorin, a furano-coumarin, has been isolated from the root.
Adulterations and substitutes
As a fibre crop, Urena lobata has to compete mainly with jute, kenaf and roselle. It is as fine and supple as jute, but not as strong. It has about the same colour and lustre as kenaf and roselle, and is finer, but less strong and durable.
Highly variable annual or perennial shrub; weedy forms low, spreading and branching, 0.5–2.5 m tall, cultivated forms erect, poorly branched, up to 5 m tall; all aboveground parts more or less densely covered with minute stellate hairs, usually also with scattered, thin, purple-tinged simple hairs; taproot 20–25(–40) cm long, with lateral roots up to 2 m long. Leaves alternate, simple, extremely variable in size and shape; stipules linear to lanceolate or obovate, 2–4 mm long, acute, caducous; petiole up to 12 cm long; blade ranging from lanceolate, orbicular or broadly ovate to shallowly or deeply palmately 3–7-lobed, 1–12 cm × 0.5–13 cm, base cordate to cuneate, apex rounded to acuminate, margin serrate to crenate, both surfaces densely stellate hairy, palmately 3–9-veined from the base, with 1–3 linear nectaries near the base of the main veins beneath. Flowers solitary or in clusters of 2–3, axillary, in the upper part of the stem seemingly arranged in spikes or racemes because of the much reduced leaves, bisexual, 2–3 cm in diameter; pedicel 1–7 mm long; epicalyx campanulate to tubular, 7–8 mm × 5–6 mm, closely enveloping the calyx and at base adnate to it, at apex with 5 long-triangular teeth 3–5 mm × 1–3 mm; calyx tubular to campanulate, 5–6 mm × 1.5–2 mm, at apex with 5 ovate to acuminate lobes 4–6 mm × 1.5–2 mm, at about one-third from the base of the slightly prominent calyx veins a nectary or a thickening only is present; petals 5, obovate, 1–1.5(–2.5) cm long, rounded at the apex, pink with a purple base inside; stamens arranged into a staminal column 10–14 mm long, usually curved, anthers in upper half, purple; ovary superior, 5-carpelled, style in the centre of the staminal column, at the apex divided into 10 arms each 1 mm long, stigmas 10, capitate, papillose, dark purple. Fruit a depressed globose schizocarp 6–10 mm wide, composed of 5 trigonous, indehiscent, mericarps, covered with barbed bristles and a thick cover of stellate hairs; mericarps trigonous, 4–7 mm × 3–4 mm, 1-seeded. Seed reniform, 2–3.5 mm wide, minutely hairy to glabrous, brown. Seedling with epigeal germination; cotyledons petiolate, with suborbiculate to reniform blade, 10–18 mm × 9–16 mm; first leaves alternate, simple, first 2 with orbicular to oblong blade, from third leaf onwards blade lobed.
Other botanical information
The taxonomy of Urena has not yet been settled. Urena has long been considered either a group of closely related species or a monotypic genus with Urena lobata as the only variable species, but at least 3 taxa in Australia are now accepted as distinct species. Like most recent African floras, this account follows the broad species approach. Within Urena lobata s.l. 2 distinct varieties are recognized for tropical Africa, based mainly on the shape of the leaves:
– var. lobata, characterized by unlobed to deeply palmately lobed leaves; the lobes usually narrowing from base to apex, but sometimes oblanceolate and widest near the apex; with narrow acute basal sinuses. It is pantropical and widely distributed in tropical Africa from sea-level up to 2100 m altitude. It is important as a source of fibre.
– var. sinuata (L.) Hochr. (synonym: Urena sinuata L.), with deeply 3–5-lobed leaves, only sometimes some scarcely or not lobed; especially the central lobes again lobed; the second-order lobes mostly broadest at the middle and broad and with more rounded sinuses leaving a large gap between the central and lateral lobes; occasionally with narrow leaves with a pair of lobes above the middle. It occurs at in Kenya, Tanzania and the Indian Ocean islands, and in Asia.
Urena is morphologically very close to Pavonia, which has mericarp bristles that are not barbed or with 3 hairy awns and leaves normally without nectaries. It is argued by several authors that the two genera should be merged.
Growth and development
Cleaned and scarified seed may germinate within 5–8 days, but germination of seed in the husk may take place over a period of 2.5 months. The growth rate during the first month is slow, but subsequent growth is fast. The time to flowering depends on photoperiod, with flowering delayed by long photoperiods. Temperature effects on flowering have not been studied. The response to daylength and the length of the vegetative period vary with genotype; sometimes small differences in daylength, as occur near the equator, may affect flower initiation. In southern Ghana continuous flowering has been observed, while in a test in the same area in southern Ghana 12 days with a daylength shorter than 12 hours were required for flower initiation. In equatorial areas flowering occurs over a prolonged period and one node may simultaneously bear all stages from flower buds to ripe fruits. The flowers open early in the morning and wither about noon. They are capable of self-pollination, but the large intraspecific variation suggests a rather high percentage of cross-pollination. The nectaries are frequently visited by ants, aphids and various Hymenoptera. Dispersal is aided by the barbed spines on the fruits which stick to clothes and to the coats of animals.
For optimal growth and fibre production Urena lobata needs a hot and humid climate with ample sunlight and rainfall, and a deep, fertile, well-drained soil. It prefers an average temperature of 21–27°C, a relative humidity of 75–85%, and a monthly rainfall of 150–200 mm during the growing season. Under less favourable conditions it may grow as a short, branched, wiry shrublet. In tropical Africa Urena lobata occurs from sea-level up to 2100 m altitude in grassland, bushland, thickets, flood plains, river banks, roadsides and fallow land, less often in semi-deciduous forest. Urena lobata can be a troublesome weed, especially in pastures.
Propagation and planting
Urena lobata is propagated with seed. The 1000-seed weight is 15–30 g and per ha about 60–80 kg unshelled seed is required, or 30–50 kg shelled seed. To obtain an even distribution of the seed, the bristly hooks should first be removed by rubbing with sand. Germination can be slow or uneven because of dormancy due to the impermeability of the seed-coat to water. It is considerably improved by shelling and scarification, for instance through removal of part of the seed-coat or treatment with concentrated sulphuric acid. Soaking in tepid water for 2 days also improves germination. Urena lobata is usually sown at the beginning of the rainy season in a well-prepared seedbed. Plants are closely spaced to prevent branching. Plant densities are usually around 300,000 plants/ha. In Sierra Leone spacings of 25 cm × 15 cm for fibre crops and 25 cm × 15 cm or 25 cm × 10 cm for seed crops have been recommended. Elsewhere a spacing of 5 cm × 5 cm has been recommended. Sowing may be done in rows (1–2 cm deep) or the seed may be broadcast.
Weeding of Urena lobata is necessary in the early growth stages and is usually done once or twice; the crop may be thinned at the same time. Urena lobata has a high nutrient demand. The nutrient uptake per hectare by a crop producing 40 t/ha green material has been estimated at 190 kg N, 24 kg P, 175 kg K and 148 kg Ca, of which 53%, 46%, 36% and 58%, respectively, is stored in the leaves. Therefore, returning the leaves to the soil helps to maintain soil fertility. In the wild state Urena lobata is a perennial, but it is usually grown as an annual crop. In some areas it is grown as a perennial, but rarely ratooned more than once. Because of the high nutrient uptake it is recommended that Urena lobata be grown in rotation.
Diseases and pests
Urena lobata can be seriously damaged by several fungi that form stem lesions (‘stem canker’). The most widespread of these fungi are Botrytis cinerea and Macrophoma urenae. Another disease is damping-off or seedling blight caused by Fusarium spp. In India Urena lobata is attacked by Corynespora callicioidea, causing scattered, yellowish-red, irregular lesions on the leaves, with a black centre that develops into a hole. The fungal diseases can be controlled by treating seed with fungicides and by crop rotation. Urena lobata is an alternate host for the okra mosaic virus.
Urena lobata is attacked by some serious pests of cotton (Gossypium spp.), kenaf, roselle and ramie (Boehmeria nivea (L.) Gaudich.), such as cotton stainers (Dysdercus spp.) and leaf rollers (Sylepta spp.). Dysdercus superstitiosus can strongly reduce the viability of Urena lobata seeds, but the fibre yield is unaffected. In Africa and Asia Urena lobata is attacked by spiny bollworms (Earias spp.). Urena lobata seems highly resistant to nematodes.
To obtain the highest yield and the best quality of fibre Urena lobata should be harvested when the plants are in full bloom. If harvested earlier, the fibre is finer but shorter and the yield is lower; if harvested later, the fibre is coarser, less white and shiny, and retting is more difficult. The plants are cut at about 20 cm above the ground, because the stem base is highly lignified and does not ret properly.
Fibre yields of 0.5–1.5 t/ha are normally obtained from Urena lobata in farmers’ fields, while experimental yields of up to 3.6 t/ha have been recorded. Yields from wild stands are only about 300 kg/ha. In 1991 the average yield in DR Congo was reported to be 720 kg/ha. In India the cultivar JRU 415, spaced at 30 cm × 6 cm and fertilized with 60 kg N, 40 kg P and 60 kg K per ha, has yielded 2.85 t/ha.
Handling after harvest
After harvest the plants are sometimes defoliated directly or after having been piled for 2–4 days to promote leaf shedding. Subsequently, the stems are tied in bundles with a diameter of 20–35 cm and retted in running or stagnant water for 7–20(–30) days, depending on water temperature and age of the stems. The bundles are suspended at least 10 cm below the water surface to prevent discolouration by sunlight, but above the bottom to prevent uneven retting or staining. The water should be clean and free of iron or other chemicals which can stain or change the colour of the fibre. After retting the fibre is stripped from the stem by hand, washed and dried in the sun. Sometimes the dry fibres are rubbed between the hands to increase lustre and suppleness and to remove any remaining extraneous matter. After retting a trained person can produce about 4 kg fibre per day. A raspador type of decorticator can also be used for fibre extraction. The fibres are graded according to quality, colour, length and strength, but grading systems vary among countries.
In view of its wide distribution, Urena lobata does not seem threatened by genetic erosion. In Madagascar harvesting of wild plants for fibre production is regulated by legislation to prevent overexploitation. Small germplasm collections are kept at the International Jute Organization, Dhaka, Bangladesh, and the USDA (United States Department of Agriculture) Southern Regional Plant Introduction Station, Griffin, Georgia, United States.
The variability within Urena lobata offers opportunities for selection. Cultivars with different growing period and fibre yield characteristics have been selected in various countries, such as ‘JRU 415’ in India. In West Africa ‘ex Mokwa’ from Niger State (Nigeria) is well-known selection.
Urena lobata yields fibre of good quality, comparable to jute, suitable for making sacks and paper, but it is a smaller plant, giving lower yields per hectare. In addition, jute is mainly grown in Bangladesh and India where labour costs are extremely low. On the other hand, Urena lobata is a well established crop in several parts of Africa and comparatively little research has been done on Urena lobata and the great variability of this species remains largely untapped. Therefore systematic collection and evaluation of the genetic diversity seems warranted as a first step to improve this crop. A systematic evaluation of the pharmacological properties also seems warranted.
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Sources of illustration
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- S. N’danikou, Plant Sciences Laboratory, Faculty of Agronomic Sciences, University of Abomey Calavi, 04 BP 0174, Cotonou, Benin
- E.G. Achigan Dako, PROTA Network Office Africa, World Agroforestry Centre (ICRAF), P.O. Box 30677-00100, Nairobi, Kenya
- L.P.A. Oyen, PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
Correct citation of this article
N’danikou, S. & Achigan-Dako, E.G. & Oyen, L.P.A., 2011. Urena lobata L. [Internet] Record from PROTA4U. Brink, M. & Achigan-Dako, E.G. (Editors). PROTA (Plant Resources of Tropical Africa / Ressources végétales de l’Afrique tropicale), Wageningen, Netherlands. <http://www.prota4u.org/search.asp>.
Accessed 13 November 2020.
- See the Prota4U database.