Cyathea J.E. Smith
- Protologue: Mém. Acad. Turin 5: 416 (1793).
- Family: Cyatheaceae
- Chromosome number: x= 69; all species: 2n= 138
Major species and synonyms
- Cyathea amboinensis (Alderw.) Merr., Interpr. Rumph. Herb. Amboin.: 63 (1917), synonyms: Alsophila latebrosa Wall. ex Hook. var. batjanensis Christ (1900), A. amboinensis Alderw. (1916).
- Cyathea contaminans (Wall. ex Hook.) Copel., Philip. Journ. Sci., Bot. 4: 60 (1909), synonyms: Chnoophora glauca Blume (1828) [not Cyathea glauca Bory (1804)], Alsophila glauca (Blume) J.E. Smith (1841), A. contaminans Wall. ex Hook. (1844).
- Cyathea junghuhniana (Kunze) Copel., Philip. Journ. Sci., Bot. 4: 58 (1909), synonyms: Alsophila junghuhniana Kunze (1848), Hemitelia javanica Presl (1851), H. junghuhniana (Kunze) Mett. (1859).
- Cyathea lurida (Blume) Copel., Philip. Journ. Sci., Bot. 4: 45 (1909), synonyms: Chnoophora lurida Blume (1828), Alsophila kingii Clarke (1883), Cyathea kingii (Clarke) Copel. (1909).
- Cyathea moluccana R. Br. in Desv., Mem. Soc. Linn. Paris 6: 322 (1827), synonyms: Schizocaena brunonis J.E. Smith ex Hook. (1838), Cyathea brunonis (J.E. Smith ex Hook.) Wall. ex Hook. (1844), C. pinnata Roxb. (1844).
- General: tree ferns (En)
- Indonesia: paku tiang, paku pohon
- Malaysia: paku gajah (Malay), paku papan (Orang Asli)
- Vietnam: ráng tiên tọa.
- C. amboinensis : Indonesia: paku itam (Malay, Ambon), hahuru meten (Ambonese), lemputu (Balinese).
- C. contaminans : Blue tree fern (En)
- Indonesia: paku pohon (general), pakis arjuno (Javanese), paku tihang bodas (Sundanese)
- Malaysia: paku gajah gunung (Malay), suo luo (Chinese)
- Philippines: pakong buaya, anonotong, gantaw
- Thailand: hua ai pet (central)
- Vietnam: ráng tiên tọa bần, răng dê thân gỗ.
- C. junghuhniana : Indonesia: paku lutung, paku reong (Sundanese).
- C. lurida : Indonesia: paku tihang beureum (Sundanese).
- C. moluccana : Indonesia: paku itam paya (general)
- Malaysia: paku gajah paya, paku hitam paya, paku pahat (Malay).
Origin and geographic distribution
Cyathea comprises 600-650 species and is distributed in the warmer parts of the world, including the tropics and subtropics, but not in the north-temperate zone or in dry areas. The greatest variety is found on tropical mountains. In South-East Asia about 200 Cyathea species are known. C. amboinensis is a native of Indonesia (Sulawesi, Moluccas). C. contaminans occurs naturally from northern India throughout South-East Asia. C. junghuhniana is confined to Indonesia (Sumatra, Java). C. lurida occurs in Indonesia (Sumatra, Java), Peninsular Malaysia and the Philippines. C. moluccana occurs naturally in Malaysia (Peninsular Malaysia, Sarawak, Sabah), Brunei and Indonesia (Sumatra, Kalimantan, Sulawesi, Moluccas). Numerous species are also cultivated as ornamentals.
Young leaves of most tree ferns are edible. After peeling or scratching off the outer layer, the young curled-up leaves are cut into small pieces and steamed, boiled or scalded and eaten as a vegetable and also used as an ingredient in more complicated dishes containing coconut milk, spices and relishes. Young leaf rachises of C. contaminans are peeled to remove the spines, then cut into pieces and steamed or cooked and eaten with "sambal". Older leaves are sometimes used as forage. The starchy pith of the stem is used as food in some countries. When trees are cut for this purpose the top of the stem is cut off to lengths of about 0.3 m, the pith being cut further into smaller pieces and steamed with rice. The mixture of cooked rice and fern pith is said to have a fresh and rather pleasant taste, but in general it is considered as subsistence food at present, as the starch content is not very high and the resulting meal not particularly palatable.
Tree ferns are grown in gardens as ornamentals and C. contaminans is the largest and most handsome one but many other species are also attractive. The fibrous root-encrusted trunks of tree ferns are a source of fern-fibre. The trunks with larger amounts of fibre are cut down, planted upside down in decorative gardens (mostly in the urban areas) or used as a substrate for certain types of epiphytic ferns and orchids. Often the fibre is cut off in slabs and used for a similar purpose. Crushed fibre is also used as a growing medium, pure or in mixtures with other material. The mass of adventitious roots at the base of the trunk of several species has a pot-like shape and is often used for potting orchids. In some countries a regular industry has been established around the supply of tree fern fibre to horticulturists.
In New Zealand a small, cottage-scale industry has developed around the production of lamp stands and bases turned from the trunks of Cyathea on a wood lathe; the turning reveals the intricate interwoven design of the dark structural material of the trunk and leaf gaps. This is an industry that would lend itself to village communities in Papuasia, but has not yet been introduced. The stems are also cut and carved as ornamental vases and other objects such as pencil and umbrella holders. Any part is used for inlaying and to make small fancy boxes and frames. "Bull roarers" are made from the woody parts of the trunks of C. contaminans and used on ceremonial occasions (a bull roarer is a flat piece of wood attached to a 1 m long string, making a roaring sound when it spins in the air while the string is swung around). In New Britain the wood is used for crafting fishing spears.
Old tree fern trunks are strong and remarkably durable and can be used for building and hedging. In the highlands of New Guinea the common grassland tree ferns at middle altitudes ( C. angiensis (Gepp) Domin, C. contaminans , C. magna Copel.) are used as picket fences for gardens and as posts on which huts are built. These tree ferns are very common in the grasslands and in disturbed areas such as abandoned garden sites. After the fern has died, the pulpy pith collapses but the strongly developed sclerotic strands remain. The trunk commonly attains heights of over 5 m, and its lower half is covered with a dense fibrous sheath of tightly interlocking sclerotic roots which provide substantial support. The structural elements of the tree fern trunks are very durable, even in permanent contact with the ground, being immune to attack from nearby decay-causing organisms. For fences the trunks are planted upside down, next to each other in a row, and lashed together to form a palissade to keep out pigs. For house posts the trunks are also planted upside down and then a deep notch is cut in the wider fibrous end to receive the floor joints. The fibrous bases of the trunks are sometimes incorporated in the house ridge poles or centre poles so that they extend out from the roof; they are then decorated with various species of ferns or orchids. Less commonly they are carved with designs or faces. They are also hollowed out and used as beehives by the Dusun community of Sabah (Malaysia). In Java the hollowed tree trunks have been filled with carbide to make canons for celebrations.
In Papua New Guinea several species are used to produce salt. Their use in farm management plans to soak up excess nutrients and as weed eradicators is questionable.
In Peninsular Malaysia poultices of the leaves are used to treat sores on the legs (e.g. of C. moluccana ) while infusions of leaves are applied against worms. The hairs on young parts of several species have styptic properties and are used to stop bleeding. Leaves of the African species C. manniana Hook. have been used to expel parasitic worms.
Production and international trade
Cyathea was included in Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) in 1975, which means that no export is allowed (except for spores and seedling or tissue cultures obtained in vitro) without prior permit issued by the CITES committee. In the past several South-East Asian countries (Indonesia, Papua New Guinea, the Philippines, Singapore) exported fern stems (e.g. to Japan) in quite large amounts. At present the trade is better controlled because a special CITES export permit is needed. For example, Indonesia has obtained a CITES-export quotum of 45 000 "stalks" for C. contaminans . All Cyathea species are collected from the wild for domestic use and there is no commercial cultivation of edible young leaves. Mature plants are dug from the wild to be grown as ornamentals but the practice is not widespread. Vases and other articles made from the stems are sold on local markets and roadsides mainly to tourists. In Australia there is a very small amount of trade in cool temperate species between specialist wholesalers of ornamentals. The Netherlands conducts some international trade in artificially propagated tree ferns.
The sclerenchyma of most Cyathea trunks is exceedingly hard and durable and provides nearly all the mechanical strength when the trunks are used as posts. It also provides an interesting pattern when cut in different ways and this effect is used in the construction of ornamental objects.
Large to very large tree ferns with small to tall, slender to robust caudex; caudex usually erect, seldom climbing or prostrate, from less than 5 cm up to 15(-20) m tall, 2-24 cm in diameter, the apex covered with scales, the surface often bearing a cover of densely matted adventitious roots and prominent leaf scars. Leaves forming a rosette at the top of the stem, essentially monomorphous, pinnately compound; petiole stout, imperfectly deciduous, short to long, bearing scales often inserted on wart to spine-like epidermal outgrowths, sometimes also hairy; pneumathodes present in a discontinuous line or 2-3 lines close together along each side of stipe and rachis; lamina more or less elliptical, lower pinnae always smaller than the middle ones or gradually much reduced and then the petiole short, small to 3.5 m × 1 m, pinnate to bipinnate-pinnatifid, hairs of various kinds rarely on the lamina surface; rachis adaxially sulcate, besides a groove in the middle additional flanking grooves may be present, stramineous to tawny, less often dark and polished, like costae with scales on abaxial and lateral surfaces, at least in early stages of growth; hairs always on upper surfaces of all but the smallest axes, antrorse, sometimes branched; pinnae up to 70 cm × 20 cm, normally again pinnatifid, in a few cases simple, in other cases fully bipinnate; pinnules up to 12 cm × 2.5 cm, almost symmetrical at the base, many on each pinna subequal, distal ones more or less abruptly decreasing; veins free, simple or branched, lower ones usually forked, sometimes pinnate where pinnule-segments are deeply lobed. Sori round, usually at the fork of veins, or seated on a simple vein, a branch of the vein always entering the receptacle; indusium present or absent, if present then either attached all around the base of the receptacle and covering the young sorus, opening to form a firm-edged cup or opening by irregular rupture, or attached on costular side of receptacle and of varying size, in some cases quite hidden by mature sorus; receptacle erect, more or less club-shaped to spherical; sporangia many, always short-stalked, annulus almost vertical, completely bypassing the stalk; paraphyses usually present as multicellular hairs, sometimes flat and several cells wide at base. Spores trilete, tetrahedral to globose, thin-walled, smooth or papillose or irregularly ridged, mostly 64, sometimes 16 per sporangium.
- C. amboinensis . Caudex 4-5 m tall. Petiole longer than 50 cm, warty near base; lamina segments firm, strongly crenate; pinnae not greatly reduced proximally, up to 50 cm long; largest pinnules up to 85 mm × 16-18 mm, sessile, lobed nearly to costa; veins in 10 pairs, costules 3.5-4 mm apart, all veins and veinlets bearing many pale bullate scales. Sori near costules; indusium a very small, dark scale on costular side of receptacle; paraphyses abundant, longer than the sporangia.
- C. contaminans . Caudex 5-15 m tall and 10-15 cm in diameter, upper part densely covered with scales of the remaining petiole-bases (only in old trees do leaf scars become visible), much thickened by adventitious roots at base. Petiole up to 1 m long, stout, usually strongly spiny, glaucous, purplish towards the scaly base; scales up to 4.5 cm × 3 mm, very thin, pale brown, with dark setae at margin; lamina 1-2 m × 1-1.5 m, green above, glaucous-green beneath, 2-3-pinnate; pinnae up to 80 cm × 30 cm, pinnules about 2.5 cm apart, lanceolate, up to 15 cm × 3 cm but usually smaller, deeply lobed almost to costa, segments oblique, falcate, up to 1.5 cm × 4.5 mm, 5-6 mm apart, crenate at margin. Sori globose, near costules in a double row on the underside of pinnules in older leaves, brown, lacking indusia; paraphyses pale, not longer than the sporangia. C. contaminans is easily recognized by the glaucous, purplish and thorny stipe bases.
- C. junghuhniana . Caudex up to 5 m tall, diameter 5-7 cm, often branched, petiole bases persistent. Petiole 30-50 cm long or longer, at base with spines up to 3 mm long; scales up to 30 mm × 2 mm, dark shiny; pneumathodes 5-14 mm long in a close double or triple row; lamina 1.5-2.5 m × 1 m, 2-3-pinnate, underside grass-green, never glaucous-green; longest pinnae 55-70 cm long; largest pinnules 80-115 mm × 14-21 mm, lobed almost to costa, margin of lobes subentire to crenate; costules 3-4 mm apart, veins in 10-12 pairs. Sori globose, at underside of older leaves, in a double row near costules, brown, with hemitelioid (attached at costular side of receptacle), semicircular, often inconspicuous indusium and short paraphyses.
- C. lurida . Caudex short. Petiole long, very dark, rough near base after fall of scales; scales up to 10 mm × 1.5 mm, pneumathodes 6-9 mm long, widely spaced; pinnae 50(-75) cm long; pinnules dimorphous; largest sterile pinnules 7.5-11 cm × 1.5-2.5 cm, lobed almost to costa, ultimate segments strongly crenate; costules 3.5-4.5 mm apart, veins up to 10 pairs; fertile pinnules much smaller, 6-9 cm × 0.6-1.2(-1.7) cm, costules commonly 3 mm apart, on largest leaves occasionally up to 6 mm, segments then separated by wide sinuses. Sori almost completely covering the lower surface of segments, without indusium, paraphyses shorter than sporangia. C. lurida is easily recognized by the dimorphous pinnules with sori completely covering the abaxial surface.
- C. moluccana . Caudex up to 50 cm tall. Petiole 20-30 cm long, dark, scaly at base, finely warty when scales have fallen; scales 15-30 mm × 0.5-3 mm, edges with dark setae; lamina simply pinnate, 1.5 m long or longer; pinnae oblong, 12-28 cm × 2-4 cm, base asymmetric rounded acroscopically, cuneate basiscopically, stalked to sessile and articulate to rachis, margin entire except for crenate, acuminate apex; veins in groups of 3 from the costa, further forking to give a group of 3-6 veins at the edge. Sori in 1-3 rows on each side of the midrib, commonly 4-6 on each vein group, when young usually covered by a thin translucent indusium, at maturity releasing copious, creamy-white spores; paraphyses shorter than the sporangia. C. moluccana is easily recognized as a simply pinnate-leaved species, forming only a short trunk.
Growth and development
Cyathea ferns are slow-growing plants and take many years to reach maximum height. Young leaves are produced regularly but overharvesting of young leaves for food will affect growth. Unlike ordinary trees, tree ferns cannot increase the thickness of their trunk as they grow taller and so in time they outgrow their strength. However, the trunk does increase in effective thickness, especially near the base, as a result of the growth of a dense entangled mass of stiff black roots which completely cover the original trunk, sometimes increasing its thickness several times. Tree ferns usually have a solitary growth habit but are commonly found in association with numerous plants within a small area. Sometimes they grow gregariously. For most species, little is known about the age of individual plants and the longevity of leaves. For young plants of C. contaminans the following data from West Java are available: average number of leaves on a plant 6-10; average time between the development of successive leaves 25-28 days; life of a single leaf 165-200 days; time taken for a complete renewal of the whole crown of leaves: 182-243 days; an old tree, 10 m tall, bore 12 leaves and the mean time between unfolding new leaves was 21 days.
Other botanical information
Cyathea is the only genus of the family Cyatheaceae . Little is known about its affinity to other fern families; only Dicksoniaceae is regarded as closely related. In the literature the Cyatheaceae have often been subdivided into several genera (based on presence or absence and structure of the indusium), e.g. best known are Alsophila R. Br. (without indusium), Hemitelia R. Br. (with a small indusium attached on one side of the base of the sorus), and Cyathea (with a cup-shaped indusium). The presence, however, of hybrids between those genera and the constancy of the chromosome numbers favours recognition of one genus only, the oldest genus name being Cyathea . Cyathea has been variously subdivided, but the 2 subgenera Cyathea and Sphaeropteris seem to be most accepted, mainly based on characters of the petiolar scales, and each subgenus with 2 sections and a number of subsections. The most useful feature for distinguishing species of Cyathea is the character of the scales of the base of the petiole (edge smooth, edge set with regular short oblique bristles or edge thin with irregular teeth) and scales of the leaf (scales strongly convex so as to appear inflated, or nearly flat, with the edges variously bristly or toothed). C. contaminans is the most widespread Cyathea species in South-East Asia; it has often been subdivided but most variations are based on characteristics that fluctuate with varying environmental factors. Upon wounding, the stem exudes a bright yellow gum which later turns red-brown.
Many authors have tried to distinguish both C. latebrosa (Wall.) Copel. and C. junghuhniana in West Java (Indonesia), but the former does not occur there. Fern specimens in herbaria or names in books for ferns in West Java, identified as Hemitelia latebrosa (Wall.) Mett. or C. latebrosa (Wall.) Copel. are wrong identifications for C. junghuhniana. C. moluccana was described by R. Brown in 1810, but he forgot to add a name to the fern; in 1827 Desvaux copied the description of Brown and provided the name.
The old trunks of Cyathea are the only habitats of the rootless primitive fern ally Tmesipteris spp.
Cyathea species are concentrated in the tropics where they are most numerous in montane to alpine vegetation, often in the undergrowth of moist forest, often in ravines. Some species prefer more open habitats, even swamps, and some grow preferentially in cleared areas, sometimes gregariously. C. amboinensis is found in forests at low elevations, including swamp forest. C. contaminans is common in rather open locations at 200-1600 m altitude, often abundant in forest edges along roads; it needs sun on its crown and moisture at its roots. C. junghuhniana occurs, sometimes abundantly, in mountain forest at 1000-2000 m altitude. C. lurida is common in sheltered locations on high mountain ridges where a peaty layer of forest litter occurs. C. moluccana occurs in light shade and often near streams in lowland forest and at moderate altitudes up to 900 m.
Propagation and planting
All Cyathea species can be grown from spores, but many tree ferns do not grow well at very low altitudes. Vegetative propagation by tissue culture should be utilised to minimise the destruction of wild stocks. In Java, C. contaminans and C. junghuhniana often start growing as weeds in tea plantations.
To grow Cyathea , the soil should be poor and wet and plants prefer initially a high relative humidity and partial shade, although the requirements differ per species. Too much exposure to sunlight will often result in burnt leaves. Waterlogged conditions are detrimental for most species.
Diseases and pests
Cyathea growing in natural stands is generally free from serious diseases and pests. Caterpillars of various insects may consume the young leaves when grown in gardens. Mealy bugs may cause problems in plants kept indoors as they hide deep in the crown and the unfurling croziers make it difficult to eliminate this pest. They are spread by ants and seem to reappear every year, usually in warmer weather.
Young Cyathea leaves are harvested from mature ferns. Tree ferns harvested for the trunk are tall trees at least 10 years old.
Genetic resources and breeding
Although Cyathea ferns are easily found in the wild at higher altitudes, many species are depleted, becoming rare due to overexploitation for food, medicine, ornamental collections and building material. Harvesting of tree trunks and piths is destructive as the plants are solitary and slow growing. Endemism is a common feature in Cyathea . Many species are confined to their own mountain tops. All Cyathea species are included in Appendix II of CITES, and several figure on the IUCN Red List. Collection and conservation of all Cyathea species, in situ and in germplasm collections, is urgent to ensure that no species are lost forever.
Cyathea ferns are attractive for growing in gardens and the stems are used to make decorative and ornamental items. There are good prospects for tree ferns in landscaping. Existing knowledge on propagation of tree ferns from spores and by tissue culture should be promoted to be used by commercial nurseries to alleviate pressure on wild Cyathea populations.
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- Holttum, R.E., 1966. A revised flora of Malaya. 2nd Edition. Vol. 2. Ferns of Malaya. Government Printing Office, Singapore. pp. 115-128.
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- World Conservation Monitoring Centre, 1995. International trade in tree ferns - an evaluation of the application of CITES; a status report. 16 pp + annexes (31 pp.). |6| Zamora, P.M. & Co, L., 1986. Economic ferns, endemic ferns, gymnosperms. In: Umali, R.M. et al. (Editors): Guide to Philippine flora and fauna. Vol. 2. Natural Resources Management Center, Ministry of Natural Resources and University of the Philippines, Quezon City, Philippines. pp. 27-28, 109-119.