Helicteres isora (PROSEA)
- Protologue: Sp. pl.: 963 (1753).
- Family: Sterculiaceae
- Chromosome number: 2n= 18
- Helicteres grewiaefolia DC. (1824),
- H. roxburghii G. Don (1831),
- H. chrysocalyx Miq. ex Mast. (1874).
- Red isora, Indian screw tree (En)
- Indonesia: jelumpang, dlumpangan (Javanese), puteran (Sundanese)
- Malaysia: chabai tali, chabai lintal, kayu ulas
- Burma (Myanmar): thoo-gnaichay
- Thailand: po pit (central, northern), cho (Karen, Chiang Mai), po thap (Chiang Mai)
- Vietnam: duôi chôn.
Origin and geographic distribution
H. isora is distributed from India, Pakistan, Nepal and Sri Lanka through Burma (Myanmar), Thailand, Indo-China, Malaysia and Indonesia to southern China and northern Australia. It is occasionally grown in Java.
H. isora yields a bast fibre used in Java for tying and for making ropes, and formerly in West Java (Indramayu) for making sacks. In India it is known as "kaivun fibre" and is used for making ropes and sacks and as supplementary raw material for paper making.
In Indonesia, Malaysia, Thailand and India the fruit (known in the Javanese medicine trade as "(buah) kayu ules", "kayu puter" or "ulet-ulet") is used internally or externally against intestinal complaints, particularly in children. In Malaysia and southern Thailand the dried fruit is employed in compound tonics, especially those given after childbirth. H. isora also has ornamental value. In India H. isora is not only used for fibre (stems and twigs) and medicine (fruits) but also for fodder (leaves and tender branches), fuel (wood) and gunpowder (charcoal).
Production and international trade
The processing of fibre obtained from H. isora bark into bags and canvas was an important cottage industry in certain parts of India at the beginning of the 20th Century, but its importance declined with the advent of jute (Corchorus spp.). Recent information on production is not available.
Fibre from the bast of H. isora has a light brown to silver colour. The length of the ultimate bast fibre cells ranges from (0.7-)1.4–1.9(-2.6) mm, the width ranges from (7-)15-17(-23) μm, and the average cell-wall thickness is 6 μm. The lumen is irregular, compressed and obstructed. The fibre surface is also irregular, with frequent constrictions and depressions. The fibre contains 73-75% holocellulose, 13% hemicelluloses and pectin, 12-23% lignin and 1-2% ash. The intrinsic strength measured was 0.987 g/denier and the elongation at break was 5.6%. The fibre has been described as soft, silky and lustrous, but also as coarse, hard, with poor lustre and of poor quality. This difference may be due to the age of the harvested stems. The orientation of the fibre bundles is very irregular and the fibre is difficult to separate into individual strands.
The wood of H. isora is suitable for paper making. Pilot studies have shown that 35-36% easy-bleaching pulp can be obtained on a large scale from unbarked or barked material using the sulphate process. Printing paper may be produced from H. isora pulp only, but for the production of writing paper a 40% admixture with long-fibre pulp is considered necessary. Laboratory experiments have shown that the soda process can produce a pulp with satisfactory strength properties. The wood fibres are (0.4–)0.9(-1.3) mm long and (10–)17(-23) μm wide.
Though it has been suggested that the use of H. isora fruits against intestinal problems has more to do with their intestinal-like twisted appearance than with their medicinal properties (Doctrine of Signatures), recent in vitro and in vivo studies indicate that the fruits have antispasmodic activity. Water extracts of H. isora fruits have shown inhibitory activity against reverse transcriptase from avian myeloblastosis virus (AMV-RT) and activity against human immunodeficiency virus type 1 (HIV-1). Neolignans isolated from H. isora have shown some inhibitory activity against AMV-RT. Other compounds isolated from H. isora include flavonoids, cucurbitacins and rosmarinic acid derivatives.
Adulterations and substitutes
The bast fibres of Helicteres hirsuta Lour. and H. viscida Blume are similarly used for making rough cordage, and their vernacular names and those of H. isora show some overlap, e.g. in Indonesia ("jelumpang" for H. hirsuta and H. isora; "dlumpangan" for H. isora and H. viscida) and Vietnam ("duôi chôn" for all 3 species).
- A shrub or small tree, 2-4(-8) m tall, bark finely wrinkled, lenticellate, pale, all young parts often densely clothed with long, yellowish, stellate hairs.
- Leaves arranged in two vertical rows, simple; stipules filiform, 3-10 mm long, caducous; petiole up to 4 cm long; blade round to obovate, 5-21 cm × 3-18 cm, base rounded to subcordate, sometimes oblique, margins irregularly serrate, apex rounded to acuminate, palmately 3-5-veined, sometimes slightly lobed near the apex, variably covered with simple and stellate hairs, often densely so on underside.
- Inflorescence an axillary fascicle of usually 2(-5)-flowered cymes with small, sessile, basal glands; peduncle 2-5 mm long; bracts linear, 3-5 mm long.
- Flowers bisexual, irregular, about 2.5 cm in diameter, fragrant; pedicel up to 1 cm long; bracteoles linear; calyx tubular, 1-2 cm long, yellow, with 5 triangular, unequal lobes, the 2 inferior lobes connate almost to the apex, the 3 superior lobes separate; petals 5, unequal, clawed, 3-4 cm long, bluish at anthesis but turning bright red, the 2 broader lower petals about 3 cm × 1.5 cm with a short claw which is winged or widened towards the apex, the 3 upper petals narrower, about 1 cm × 0.5 cm, with a claw up to 2.5 cm long which is auricled near the apex; gynandrophore 3-6 cm long with red apical glands; staminal tube 2.5 mm long, making an angle of 90with gynandrophore, terminated by 10 stamens (filaments connate in lower 2/3) and, more inwardly inserted and often hidden by the stamens, 5 staminodes; filaments short, anther cells 2, parallel with each other; pistil with 5-celled, red-glandular ovary and 5 subconnate, short styles.
- Fruit consisting of 5 twisted follicles, 4-8 cm long, each follicle about 20-25-seeded.
- Seed angular-subrhomboid, about 2.5 mm × 1.5 mm × 2.7 mm, finely warty, glabrous, dark brown.
Growth and development
In Java H. isora flowers throughout the year; in Indo-China flowering and fruiting has been observed in June. Flowers open early in the morning (3-3.30 a.m.) and last for 2-3 days. At anthesis the petals are strongly recurved to a vertical position, blue-grey, turning violet in the afternoon, becoming dark red in the evening. The second day the petals have curved halfway upward to a horizontal position and the top of the style bears a sticky droplet. Flowering on the first day is functionally mainly male and on the second day female. H. isora flowers are pollinated mainly in the morning by birds, that are attracted by the flower colour and by the fragrant nectar. Both self- and cross-pollination are possible. H. isora coppices well and survives burning, with rapid regrowth after cutting or burning.
Other botanical information
Based on the degree of hairiness several subclassifications of H. isora have been made which have no practical value. The genus Helicteres L. comprises 60 species, of which 38 are in tropical America, none in tropical Africa and 22 in tropical Asia and Australia, with none of the species occurring in both tropical America and Asia/Australia. The American species were revised taxonomically in 2001, but the Asiatic ones need a critical revision. In South-East Asia several other Helicteres spp. are or have been used as a source of bast fibre. Those mentioned include H. angustifolia L. (China, Taiwan, Japan, throughout South-East Asia to Micronesia; a shrub up to 1 m tall), H. hirsuta Lour. (South-East Asia, not in Borneo, Moluccas and New Guinea; see minor fibre plants), and H. viscida Blume (Burma (Myanmar), Thailand, Indo-China, Peninsular Malaysia, Java; see minor fibre plants).
H. isora is a gregarious species common in evergreen forest and secondary jungle along roads and forest edges. In Java H. isora is found in relatively dry areas up to 300 m altitude, the habitats including teak forest, brushwood and roadsides. In Thailand it is found in deciduous forest and scrub areas. Fertile soils rich in humus are preferred; in sandy and lateritic soils the plants are stunted, much branched, and with a very thin bark. In Hainan (China) H. isora is a common weed in sown pastures.
Propagation and planting
H. isora is easily propagated by seed, but vegetative propagation with stem cuttings is also possible. Seeds may be sown in a nursery and the seedlings planted out into the field later. Close planting, with e.g. distances of 60-90 cm, results in long, straight stems, whereas wider planting leads to profuse branching and thus lower fibre quality.
Material from H. isora is usually collected from the wild. H. isora can be grown as a coppice crop, with yearly cutting.
Diseases and pests
In India the weevil Myllocerus viridanus (Curculionidae) can cause serious defoliation of H. isora. No information is available on diseases and pests of H. isora in South-East Asia.
Traditional practice in India is to harvest H. isora stems about 2.5 cm in diameter for fibre extraction.
Recent and reliable information on H. isora yields is not available.
Handling after harvest
H. isora fibre is extracted from the stem by retting. For sack-making in West Java (Indramayu) the stems were tied into bundles and retted for 1-4 weeks, depending on water quality and stem age (older stems needing a longer retting period), yielding fibre ribbons of 2–3 m length. In India the traditional method is to remove the leaves and keep the stems submerged in a stream or pond for 18-24 days. Retted stems are taken out of the water and gently beaten with wooden mallets, after which the fibres are peeled off, washed and dried in the sun. Retting in running water is preferable to obtain fibre of good colour and quality. In an Indian study, H. isora stems, varying in age from 6 months to over 2 years, were cut in pieces 0.9 m long, tied in bundles and submerged in a tank, with the water being changed frequently to keep the fibre clean and white. It took 15-22 days for retting, with the younger stems being ready earlier than the older ones. When retting was complete the bundles were taken out, the fibre was stripped manually from the stems, cleaned, washed in clear water and dried in the sun. It was found that fibre obtained in this way from stems 1-2 years old was soft and strong, but that from stems older than 2 years was coarse and brittle.
No germplasm collections of H. isora are known to exist. H. isora does not seem threatened with extinction.
No breeding programmes of H. isora are known to exist, though it has been proposed in India to develop improved cultivars to meet the increasing demand for its range of useful products.
In view of the lower quality and more difficult processing of H. isora compared to jute, its prospects as a fibre crop are not bright. In South-East Asia its role will probably remain limited to a local source of rough cordage, though it may offer some potential for paper production and as an ornamental shrub.
- Atluri, J.B., Purnachandra Rao, S. & Subba Reddi, C., 2000. Pollination ecology of Helicteres isora Linn. (Sterculiaceae). Current Science 78(6): 713-718.
- Bhat, R.V. & Singh, M.M., 1951. Indigenous cellulosic raw materials for the production of pulp, paper and board. Part IV. Writing and printing papers from Helicteres isora L. (maror phal). The Indian Forester 77: 664-675.
- Council of Scientific and Industrial Research, 1959. The wealth of India: a dictionary of Indian raw materials and industrial products. Vol. 5: H-K. Council of Scientific and Industrial Research, New Delhi, India. pp. 27-29.
- Cristóbal, C.L., 2001. Taxonomía del género Helicteres (Sterculiaceae) [The taxonomy of the genus Helicteres (Sterculiaceae)]. Revisión de las especies americanas [A revision of the American species]. Bonplandia 11(1-4): 1-206.
- Kamiya, K., Saiki, Y., Hama, T., Fujimoto, Y., Endang, H., Umar, M. & Satake, T., 2001. Flavonoid glucuronides from Helicteres isora. Phytochemistry 57(2): 297-301.
- Sebastine, K.M., 1954. Kaivun fibre. Economic Botany 8: 114-117.
S. Brotonegoro & Wiwik Wiharti