Phormium tenax (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Phormium tenax J.R. Forster & G. Forster

Protologue: Char. gen. plant.: 47, t. 24 (1776).

Family: Hemerocallidaceae

Chromosome number: 2n= 32

Synonyms

Chlamydia tenacissima Gaertn. (1788), Phormium ramosum Billb. (1833).

Vernacular names

• New Zealand flax, phormium (En). Lin de la Nouvelle Zélande (Fr). Harakeke (Maori).

Origin and geographic distribution

P. tenax is indigenous to New Zealand and Norfolk Island. During the 19th Century it was introduced into many other countries, including Java where it is planted in gardens above 1200 m altitude. Today cultivars of P. tenax and the closely related P. cookianum Le Jolis are grown as ornamentals throughout the temperate regions of the world. Several countries other than New Zealand have grown P. tenax as a commercial fibre crop, including Argentina, Chile, Brazil, Japan, St Helena, the Azores, South Africa and Kenya. In some of these countries and in parts of the United Kingdom and Ireland it is now naturalized. In some areas of South Africa, the Hawaiian Islands, St Helena and the Azores, it has become a weed.

Uses

In New Zealand P. tenax was a vital resource to early Maori. The leaves and extracted fibre were plaited and woven to make containers, cordage, nets, clothing, sandals and matting. The dry flower stalks were lashed together and used for temporary rafts. The copious nectar from the flowers was collected to serve as a sweetener. Some of these uses continue today, in particular the plaiting of baskets and mats, the making of a swinging skirt ("piupiu") worn in cultural ceremonies and dance, and the weaving of fine cloaks from hand-dressed fibre. Traditional techniques and patterns have been maintained by Maori weavers though P. tenax is also utilized in a variety of ways in contemporary arts and crafts. In the past fibre and tow from P. tenax were used commercially to make woolpacks, baler twine (used for tying up bales of hay), ropes, carpets, mats and carpet underfelt, as a binding in fibrous plaster, for padding in upholstery, and as insulation for hot-water cylinders.

Though P. tenax has many uses in traditional medicine, it is not so widely utilized today for such purposes. Most commonly, the rhizome was boiled and the liquid used as a purgative, an anthelmintic and for stomach disorders; the rhizome also was pulped to make a poultice; the gum found at the base of the leaf was used as an antiseptic for wounds, burns and taken internally for diarrhoea; and the dressed fibre was used as a bandage.

P. tenax is grown as a shelter belt and ornamental varieties are commonly planted in gardens. Leaves of coloured varieties are used by florists.

Production and international trade

In New Zealand commercial production and export of hand-dressed P. tenax fibre began in the early 19th Century. By 1861 a machine had been developed which could mechanically strip the fibre and by the early 20th Century P. tenax was New Zealand’s major export crop. After the First World War exports gradually declined and since 1942 production has only been for the domestic market. Government subsidies for P. tenax production, together with import restrictions on jute ( Corchorus spp.) and other fibres, enabled about 15-20 mills to operate between 1950 and 1970, producing a total of 5000-6000 t of fibre per year. Government protection was removed during the 1970s and manufacturers replaced P. tenax fibre with cheaper synthetics and imports of sisal ( Agave sisalana Perrine) and jute. The last factory in operation closed in 1985. Today, there is a small cottage industry that uses P. tenax for paper making and a local market for woven crafts. There is both a domestic and international market in ornamental cultivars for gardens, and one producer exports the variously coloured leaves to florists all over the world.

Fibre produced in St Helena and the Azores was exported to the United Kingdom, at least until the 1960s, whereas P. tenax grown in South America and Africa is used domestically. Recent statistics on P. tenax production or trade in these regions are not available.

Properties

The properties of P. tenax fibre are somewhere between the hard fibres from sisal and abaca ( Musa textilis Née) and the soft fibres from hemp ( Cannabis sativa L.), jute and flax ( Linum usitatissimum L.). P. tenax fibres are highly variable in dimensions and physical properties. Each fibre strand is a composite structure of ultimate fibres of uneven thickness. The ultimate fibre cells are (2-)5-10(-20) mm long and have a diameter of (5-)14-16(-25) μm. The fibre surface is smooth. In cross-section the ultimate fibres are round or oval and have a narrow lumen. The fibre (10% moisture) contains about 45% cellulose, 30% hemicelluloses, 11% lignin, 0.7% pectin, 2.2% water-solubles and 0.7% fat and wax. The colour of the extracted fibre ranges from white to pale reddish-brown. P. tenax fibre has a high tenacity combined with a low extension at break. When dry, the fibres have tenacities similar to those of textile grade synthetic fibres, but when wet they are weaker. A recent study of 11 traditional weaving cultivars of P. tenax showed marked differences between the content, strength and extension characteristics of their respective fibres. The fibre has been pulped using the soda process, with pulp yields of 60-70%, and the pulp is suitable for writing and wrapping paper and rayon.

The rhizome contains the purgative anthraquinones chrysophanol and emodin. Cucurbitacins with antibacterial and anticancer activity have been isolated from the leaves, and the antifungal compound musizin from the roots. The seed oil is rich in linoleic acid.

Adulterations and substitutes

P. tenax can be replaced by sisal, abaca and jute, and is mixed with both jute and sisal in the production of sacks. The main competitor of P. tenax (apart from synthetic fibres) is sisal. P. tenax has some advantages over sisal: the leaves have a higher percentage of fibre, it is easier to grow and harvest and it can grow in regions where it is impossible to cultivate sisal. However, the fibre cannot be cleaned as efficiently using present technology, the cost of production is higher, and the fibre is less strong.

Description

An evergreen perennial, stemless plant, 2-5 m tall, growing in tufts, with sword-shaped leaves that grow in the form of a fan from the ends of a fleshy, creeping and branched rhizome about 5 cm in diameter. Leaves more or less erect, 1-4 m × 5-12 cm, growing in two opposite rows, strongly keeled at base, lower third or half of the leaf closely folded across its midrib so that the upper surface of the leaf lies on the inner side of the fold, yellowish-green to blue-green (underside usually blue-green), sometimes bronze or variegated, with a narrow margin coloured in shades of orange, red, brown or black, marked by numerous fine, close, longitudinal striations and strengthened by tough bast fibres. Inflorescence a panicle, up to 5 m tall, growing from the centre of the fan; peduncle 2-3 cm in diameter, usually erect, dark, terete and glabrous, with a series of alternate, sheathing, deciduous bracts of progressively smaller size, the lower ones empty, the upper ones each subtending and entirely enclosing a comparatively short, alternately branched, flowering lateral; pedicel 8-10 mm long, articulated just below the flower; flower bisexual, tubular (tepals fused at base, otherwise partly connate), up to 5 cm long, usually dark red; tepals 6, in 2 whorls, the inner slightly longer than the outer one, tips of inner tepals slightly recurved; stamens 6, inserted at the bases of the tepals, longer than the tepals, filaments filiform, glabrous, slightly flattened, anthers inserted above their base; pistil with superior, sessile, cylindrical, 3-locular ovary with numerous ovules, style filiform, stigma small, capitate stigma. Fruit an erect, 3-sided prismatic capsule, 6-10 cm long, loculicidally 3-valved, abruptly narrowed at the apex, 60-150-seeded. Seed flattened-ellipsoid, more or less twisted, 9-10 mm × 4-5 mm, glossy-black.

Growth and development

P. tenax seeds germinate in about a month. A seedling soon develops a fan of leaves which thicken at its base. Its initial taproot is replaced by numerous shallow roots, closely resembling the root system of the mature plant. Within a year a seedling can develop up to eight small fans, each about 30 cm in height. A fan of leaves may be seen as the unit of the plant. Young leaves arise continually from the centre of the fan, while the older leaves on the outside die away. Each fan usually has about 8 or 10 leaves, though they can have as many as 20 or 30. As the plant increases in age, the rhizomes branch freely, usually away from the centre, forming a ring of new fans around the original old rhizome. Plants take 6-8 years to flower. In New Zealand, flowers are produced in the early summer, between November and January, though the extent of flowering throughout populations fluctuates over a 2-4-year cycle. The nectar-filled protandrous flowers are bird pollinated and preferentially out-crossed. The stalk itself is heavy and full of sap, though later it dries, becoming extremely light. From late summer, the capsules split and spill their seeds, which are adapted for wind and water dispersal. Once an inflorescence has developed, the fan from which it has risen dies in about a year.

Other botanical information

The taxonomic position of Phormium J.R. Forster & G. Forster has always been disputed, with it being classified variously in the Liliaceae, Agavaceae and Phormiaceae . At present the most accepted position is in Hemerocallidaceae , together with 12 other genera. Phormium comprises 2 species. The other species, P. cookianum , is also native to New Zealand. It has thinner, more flaccid leaves, yellowish flowers and longer, pendulous, twisted fruits, up to 20 cm long. P. tenax can hybridize with P. cookianum and such hybrids have given rise to numerous garden cultivars with coloured leaves. Maori also distinguish many cultivars of P. tenax , based on leaf and fibre qualities. Some of these named cultivars were used for breeding in the days of the flax industry.

Ecology

P. tenax grows throughout New Zealand from sea-level to about 1200 m altitude. Mature bushes are frost-hardy, though they may not withstand prolonged temperatures below freezing. Cultivation is possible in warmer regions, like St Helena, with temperatures ranging from 13-29°C, but P. tenax is not suited to tropical lowland. It grows in areas with a relatively low (500 mm) to high (3500 mm) annual rainfall. It is found on a wide range of soils, but thrives on rich, well-drained soils. Before land clearance and drainage, it was found in abundance on moist alluvial soils near rivers and swamps.

Propagation and planting

Propagation of P. tenax for small-scale plantations is done by rhizome division. Plantations of clones are ideal because they combine high quality and uniformity. A single, mature clump can provide many dozens of fans with attached rhizome. The youngest shoot is left unless it is longer than 1 m. Propagation by seed is also possible, but seedlings do not come true-to-type, even when the parents are of the same clone.

In the 1930s seedling propagation was used (along with vegetative methods) on a government-owned development plantation to increase the area under cultivation. Up to 5000 seedlings can be obtained from one inflorescence. On the development plantation the land was cleared of heavy growth, ploughed, planted with rye-grass and white clover, and grazed by sheep for 2 years. Planting was carried out in the spring, using a specially adapted tractor. Fans were planted every 1.5 m, with 2.5 m between the rows. Sheep continued to graze the land as the plants became established.

Nowadays P. tenax is no longer grown in New Zealand as a commercial fibre crop though many weavers and Maori villages have small plantings of cultivars for weaving purposes.

Husbandry

Weed control in P. tenax is essential for the first 2 years after planting. Provided weeds are kept under control, little extra care is needed. Maori weavers cut the emerging inflorescences so that the plant’s energy goes into the leaves rather than flowers, and trim the bushes of dead and diseased leaves.

Diseases and pests

The most serious disease of P. tenax , and one which contributed to the decline of its industry in the 1920s, is yellow-leaf disease. It is characterized by abnormal yellowing and dying of the leaves and stunted new growth. Underground, the roots die off and rhizome tissues collapse. Eventually the whole plant may die. The disease is caused by a phytoplasma, which is transmitted by the plant hopper Oliarus atkinsoni. The phytoplasma has been named phormium yellow leaf (PYL) phytoplasma, but recently it has been proposed that it be included in the taxon " Candidatus Phytoplasma australiense". Effective means of control are not available, though systemic insecticides may control the vector. Various fungal infections (spots and moulds) can affect the appearance of P. tenax leaves and in severe cases make fibre extraction impossible. Diseased leaves should be removed and burnt and it is important to ensure that plants have adequate air circulation.

The most serious pests for traditional weavers are the caterpillar of the windower moth ( Orthoclydon praefactata ) and the notcher ( Tmetolophota steropastis). The former chews narrow strips from the underside of the leaf, exposing the fibre which soon decays. The latter eats large U- or V- shaped notches from the edge of the leaf, rendering that part of the leaf useless for plaiting or fibre extraction. The caterpillars are nocturnal and hide by day in debris at the base of the plant. The best control method is to keep the area free of dead leaf material. Insecticides can be used, though it is often difficult to penetrate the leaf bases thoroughly, and it is probably not practical on a large scale.

Harvesting

When grown from divisions, the first harvest of P. tenax usually takes place when the plants are 4-6 years old. New Zealand weavers prefer to harvest after the plants have flowered, because it is easier to strip the fibre from the leaves at this time. The outer leaves of a fan are cut at an angle from the base of the outside leaf, leaving the growing shoot and the two blades on either side. Cut in this way, the fan is available for further harvesting within a year. In the industry days the plants were slashed with a semi-circular tool like a reaping hook, straight across the bush about 15-20 cm up from where the leaves go into the crown of the rootstock. This did not unduly weaken the plant, which was able to produce another crop in 3.5 to 4 years. Traditional weavers are able to use less mature leaves than the miller, whose machines required leaves with good body and strength.

Yield

On commercial P. tenax plantations, it took 8-10 t of green leaves to produce 1 t of fibre, depending on the variety. Using traditional techniques, the yield is much less, because comparatively little of the leaf is used. A well-established plantation yielded 75-100 t leaves/ha/ harvest.

Handling after harvest

The method of separating the fibres from the leaves of P. tenax is a central factor in the quality of the product. When hand-dressed using traditional techniques, the fibre is stripped from the upper surface of the leaf only, and scraped clean from surrounding tissue. The resulting product is much finer and softer than that extracted by machine. Machines, however, used the whole leaf and butt and could process much greater quantities of leaf material rapidly. The technology used to process P. tenax in New Zealand until most production ceased in the 1970s had changed little since the early days of the industry. Bundles of leaves were carried to the stripping mill by light railway or truck and graded into lengths. Fibre was extracted using a Booth-Macdonald stripping machine or decorticator and carried into a washing machine. Extraneous matter was washed away, and the fibre formed into hanks and hung on rails to drain. When nearly dry, the hanks were spread out on the ground or fences to bleach. The fibre was then fed through a scutching machine, whose revolving beaters removed the remaining dry matter and short or rough fibres. Fibre was made up into hanks, pressed into bales and graded according to its cleanliness, colour and strength.

Genetic resources

P. tenax is common in New Zealand, although many of the large natural stands have been converted into farmland. Individual weavers grow traditional weaving cultivars, as they have done for generations. Landcare Research, a government-owned research institute in Lincoln, New Zealand, maintains a living collection of both traditional named weaving selections and cultivars bred for commercial use.

Breeding

In New Zealand no breeding programmes for P. tenax suitable for fibre exist anymore. Horticulturists breed P. tenax for garden and landscaping use, selecting for size, form and leaf colour.

Prospects

There are no immediate prospects for the re-establishment of a P. tenax fibre industry in New Zealand. It is unlikely that a commercial fibre industry could be established unless a method is developed to extract the fibre in a way that ensures a quality matching that of hand-dressed fibre. However, the local use of P. tenax as a medium in arts and crafts, both traditional and contemporary, is strong and continues to grow. In experimental plantings in the Cameron highlands in Malaysia in the 1950s P. tenax grew very well and good quality fibre was prepared from sample leaves. At the time, it was considered a useful crop for valley bottom highland soils too wet for tea ( Camellia sinensis (L.) Kuntze). However, with other fibre plants more suited to a tropical climate and producing earlier than 4 years after planting, there seems little benefit in considering P. tenax as a fibre crop for South-East Asia.

Literature

• Atkinson, E.H., 1922. Phormium tenax. The New Zealand fibre industry. Bulletin No 95 (new series). New Zealand Department of Agriculture, Wellington, New Zealand. 53 pp.
• Critchfield, H.J., 1951. Phormium tenax - New Zealand’s native hard fiber. Economic Botany 5: 172-184.
• Harris, W. & Woodcock-Sharp, M., 2000. Extraction, content, strength, and extension of Phormium variety fibres prepared for traditional Maori weaving. New Zealand Journal of Botany 38: 469-487.
• Kirby, R.H., 1963. Vegetable fibres: botany, cultivation and utilization. Leonard Hill, London, United Kingdom & Interscience Publishers, New York, United States. pp. 284-296.
• Moore, L.B. & Edgar, E., 1976. Flora of New Zealand. Vol. 2. Government Printer, Wellington, New Zealand. pp. 51-52.
• Scheele, S., 1997. Insect pests and diseases of harakeke. Manaaki Whenua Press, Lincoln, New Zealand. 27 pp.
• Scheele, S. & Walls, G.Y., 1994. Harakeke. 2nd Edition. The Rene Orchiston collection. 24 pp.
• Twose, M.F., 1988. Studies of Phormium tenax prepared in the traditional Maori manner. MSc. Thesis, University of Otago, Dunedin, New Zealand. 150 pp.

Authors

S. Scheele