Pteris (PROSEA)

Plant Resources of South-East Asia
Introduction

Protologue: Sp. pl.: 1073 (1753).

Family: Pteridaceae

Chromosome number: x= 29;P. cretica: 2n= 58 (diploid), 87 (triploid), 116 (tetraploid), reproduction apogamous;P. ensiformis,P. multifida,P. semipinnata,P. vittata: normally 2n= 116 (tetraploid), reproduction sexual, but other ploidy levels and counts exist as well

Major species and synonyms

Pteris cretica L., Mant. pl. 1: 130 (1767).

Pteris ensiformis Burm.f., Fl. indica.: 230 (1768), synonym: P. crenata Swartz (1801).

Pteris multifida Poir., Encycl. 5(1): 714 (1804).

Pteris semipinnata L., Sp. pl.: 1076 (1753).

Pteris vittata L., Sp. pl.: 1074 (1753), synonyms: P. longifolia auct. non Retz. (1883), P. longifolia L. var. brevipinna Domin. (1913).

Vernacular names

P. cretica .

Cretan brake (En)
Thailand: kut phi sue (northern), foen ngoen (Bangkok)
Vietnam: ráng chân xì hy lạp.

P. ensiformis.

Sword brake, slender brake, laurel fern (En)
Malaysia: paku padang, paku mega, paku mukut
Philippines: pakong parang.
Singapore: chièn yèh fèng weich'uéh
Thailand: foen ngoen
Vietnam: ráng chân xì hình gượm.

P. multifida.

Spider brake, huguenot fern, Chinese brake (En, Am).
Vietnam: phượng vì thảo, seo ga, theo ga.

P. semipinnata

Malaysia: paku medang, paku pelandok.

P. vittata . Rusty brake, ladder brake, Chinese ladder brake (En, Am)

Malaysia: paku uban bukit. Singapore: líng kaì fèng weich'uèh
Thailand: kaching duphae, kut tat, kut mak (northern).
Trade name: Pteris longifolia.

Origin and geographic distribution

Pteris comprises an estimated number of 240-300 species and is distributed worldwide in tropical and temperate moist areas. About 80 species are found in South-East Asia.

P. cretica occurs almost pantropically and in many subtropical areas. Since it has been widely cultivated and freely naturalized, the origin is uncertain.

P. ensiformis naturally occurs in Sri Lanka, India, China, throughout South-East Asia to northern Australia and Polynesia, and is widely naturalized elsewhere.

P. multifida occurs from Japan to Indo-China and Singapore and is naturalized in various locations in the Americas.

P. semipinnata is distributed from southern Japan and southern China throughout South-East Asia. The natural southern limit is uncertain but it is naturalized in northern Australia.

P. vittata is very widespread in the warm tropical and temperate Old World: from Japan to northern Australia, Polynesia, Yemen, the Comoros and Mascarene Islands, from Spain to South Africa, and is naturalized in South America, for example in the Caribbean.

Uses

Various species of Pteris are used as ornamental plants (e.g. P. cretica , P. ensiformis , P. quadriaurita Retz., P. semipinnata , P. tripartita Swartz, P. vittata ). The leaves of P. ensiformis possess astringent properties, and a decoction of the fresh leaves is given in dysentery. In Malaysia the juice of young leaves is applied to clean unhealthy tongues of young children, while the juice of the rhizome has an application for glandular swellings of the neck. In New Guinea the juice is used for boils, ulcers, and wounds. The use for controlling menstruation is also reported from Papua New Guinea. P. moluccana Blume is used as a vegetable or to wrap food in Papua New Guinea while the salted raw shoots are given to children as a tonic. A decoction of roots and leaves of P. multifida is applied medicinally in Vietnam to treat diarrhoea and dysentery, and as an anthelmintic. The ground dried roots and leaves boiled in sesame oil are used to treat skin diseases in children. The raw leaves of P. tripartita and the closely related P. wallichiana J. Agardh are used during childbirth in Bougainville and Papua New Guinea. The roasted white pith of the petiole is applied as an anthelmintic to treat round worms. A number of species is used in Chinese medicine. P. altissima Poir. is used in Honduras as a skin cleanser and to alleviate insect bites. Stands of P. vittata have been suggested to remedy arsenic contaminated soils but no field test results are available yet.

Production and international trade

An extensive trade exists in various species, varieties and cultivars of Pteris , but no statistics are available.

Properties

P. vittata accumulates metallic ions (As, Cd, Cu, Fe, Mn, Pb and Zn) from the soil and the uptake of arsenic is especially prominent. P. vittata actually profits from soil arsenic concentrations up to 100 ppm as compared to clean soil, and a biomass increase of up to 107% has already been observed at around 50 ppm. At soil arsenic concentrations exceeding 500 ppm the growth is reduced, although the plants may survive a much higher pollution. Bioaccumulation factors up to 142 are found (a total accumulation of arsenic over 22 500 mg/kg on a dry weight basis) with 75-98% of the element accumulated in the aboveground parts of the fern, thus removing up to 26% of the arsenic in the soil. Little difference in solubility exists among the various arsenic compounds except for FeAsO₄and AlAsO₄, which are less soluble. In addition to arsenic, P. vittata is also effective in accumulating phosphorus; depending on the soil phosphorus concentration, accumulation factors up to 55 have been found.

Three unnamed compounds of P. semipinnata (A, 5F, and especially 6F) inhibit the activities of DNA topoisomerase I and II, and show strong cytotoxic activity against human cancerous cell lines. At low concentrations compound 6F enhances the cytotoxicity of genistein against a cancerous cell line by factor 2.60 to 4.65. Two diterpenes from the aerial parts of P. multifida showed a moderate cytotoxicity to Ehrlich ascites tumour cells. On the other hand, extracts of spores from P. vittata induced DNA damage in human cells in vitro. Ptaquiloside, the sesquiterpenoid carcinogen of Pteridium aquilinum (L.) Kuhn, was isolated from P. cretica . Antimicrobial activity against Candida utilis , Micrococcus luteus and Staphylococcus aureus has been demonstrated for alcohol extracts of P. ensiformis , and against Bacillus subtilis for P. inaequalis Bak. Water extracts of the rhizomes and leaves of P. vittata inhibit germination of spores and growth of Alternaria brassicicola and Aspergillus niger . Luteolin, apigenin, β-sitosterol and daucosterol were isolated from the acetone-methanol extract of the aerial parts of P. multifida . Luteolin inhibited the growth of Bacillus subtilis and Candida albicans . The presence of the anti-allergic compound asperglaucide has also been demonstrated. Essential oils were isolated from P. cretica and P. multifida . The components included in both oils were quite similar, the major common compounds found being hexanal, vanillin, 4-hexen-1-ol, 1-hepten-3-ol, 3-hydroxy-2,2,4-trimethylpentyl-isobutyrate, carbonyl compounds, alcohols and esters such as heptanal, isobutyl-isobutyrate, and ethyl-cinnamate. Both oils possessed a green and seaweed odour. Pterosin derivatives are found in P. semipinnata and P. wallichiana . Pterosins have been shown to inhibit calcium contractures of potassium-depolarised smooth muscle of guinea-pig ileum by both histamine and acetylcholine. A diterpene and 2 indanone sesquiterpenes are found in P. angustipinna Tagawa, P. cretica , P. dactylina Hook., P. grevilleana Wall. ex J. Agardh, P. multifida and P. tremula R. Br. Four more ent-kaurane-glycosides were isolated from the leaves of P. cretica . A C-glycosyl-flavone-O-glycoside from aerial parts of P. cretica was characterised as luteolin-8-C-rhamnoside-7-O-rhamnoside. The flavone glycosides luteolin-7-O-robinobioside, luteolin-7-O- rutinoside, luteolin-7-O-glucoside, luteolin-7-O-β-sophoroside and luteolin-7-O-β-gentiobioside were isolated and identified in this plant material. The flavonoids 3-C- (6-O-acetyl-β cellobiosyl)-apigenin and 6-C-β-cellobiosylisoscutellarein-8-methy-ether are found in P. vittata .

Description

Terrestrial or epilithic, small to very large ferns with linear, marginal sori. Rhizome erect or short-creeping, slender to massive, often stout; scales always present, elongate or narrow, entire or rarely dentate, brownish to blackish, sometimes with a pale margin, glabrous, often sclerotic, non-clathrate, attached by a broad base, often also with hairs. Leaves closely spaced, 1-2(-5)- pinnate, sometimes tripartite, palmate or pedate, monomorphic or dimorphic; petiole adaxially grooved, stramineous, reddish, brown to purple, or dark and lustrous, the basis with scales and hairs like the rhizome, with one or less often two vascular bundles; lamina apex often similar to a pinna, thin-herbaceous to coriaceous, glabrous or less often variously hairy, the basal pinnae often branched and strongly produced basiscopically, seemingly bifurcate; rachis deeply grooved continuous into the costae, frequently alate, especially the distal part; costae with the groove margins frequently interrupted and producing teeth or spines; venation entirely catadromous, or the basal pinnae anadromous, free or areolate. Sori linear, marginal to submarginal, when young covered by a false indusium formed by the deflexed margin of the segment; paraphyses usually present, then often in great number. Spores tetrahedral or globose, rugose, reticulate or papillose, pale to almost black.

P. cretica . Rhizome short creeping; scales minute, dark brown, entire. Leaves once pinnate, except for the basal pinnae that are forked once or twice, dimorphic; petiole slender, 10-50 cm long, stramineous to purple, nearly black at the base, glabrous or puberulous; lamina oblong, 15-40 cm × 6-35 cm, pinnae up to 7 pairs, up to 23 cm × 2 cm, fertile pinnae up to 1.2 cm wide; pinnae margins serrate; veins free.

P. ensiformis . Rhizome slender, creeping or suberect, bearing leaves close together; scales dark brown, concolorous, entire. Leaves distinctly dimorphic; petiole 5-30 cm long, pale green or stramineous, glabrous; sterile lamina oblong, 7-30 cm long, with usually pinnate lower pinnae, apical part simple, below tripinnatifid or pinnate with 1-3 lobes or pinnules; fertile leaves taller, bipinnate, pinnae of fertile leaves forked once near the base only, the lobes much narrower than in sterile pinnae, up to 40 cm long, with simple terminal segment, 15-25 cm long, below this about 3 pairs of oblique ascending pinnae, each shaped like the terminal segment but usually with a short branch on the basiscopic side near the base; veins free.

P. multifida . Rhizome short-creeping; scales small, blackish-brown. Leaves bipinnate with long, rarely forked pinnules, dimorphic; petiole slender, 4-25 cm long, stramineous, darker at the base, glabrous; lamina ovate, 20-30(-45) cm × 15-25 cm, rachis alate by the decurrent pinnae bases; pinnae about 4 pairs, up to 10-15 cm × 3-10 mm; fertile leaves more divided and with narrower segments; veins free.

P. semipinnata . Rhizome short, erect; scales narrow, dark brown, entire. Leaves pinnately pinnatifid, monomorphic; petiole slender, 10-40 cm long, dark purplish, glabrous; lamina deltoid, 30-40 cm long, pinnae 6-12 pairs, up to 5-10 cm long, basiscopically dissected into 3-more lobes, acroscopic margin entire; fertile pinnae narrower than the sterile pinnae; veins free.

P. vittata . Rhizome short, erect to suberect, covered with concolorous, brownish, entire scales. Leaves pinnate, monomorphic; petiole 5-50 cm long, green, scaly throughout when young; lamina oblanceolate, (15-)25-50(-80) cm × (6-)13-25 cm with much longer terminal segment; pinnae up to 15 cm × 7-10 mm; sterile and fertile leaves only slightly different; veins free.

Other botanical information

Pteris is a large, morphogically diverse genus, comprising 240-300 temperate to tropical species, including numerous complexes varying from a few to several dozen species. Polyploidy occurs in 55% of its species and apogamy in 35%. The genus is in need of a modern revision. From detailed karyological studies in P. vittata it is clear that it is a coenospecies or species complex having five cytotypes (diploid to hexaploid). The diploid and tetraploid types are sexual with normal divisions whereas the triploid, pentaploid and hexaploid ones are natural hybrids and have arisen in nature from hybridization between different genotypes. P. vittata was formerly confused with the neotropical P. longifolia L. and in trade it still persists under this name. The American P. longifolia differs from the Asiatic species in a number of aspects including the articulate and deciduous pinnae.

The popularity of the genus as ornamentals has given rise to a great number of cultivars (e.g. about 250 for P. cretica ), often with variegated or strongly divided leaves.

Ecology

Pteris occurs worldwide in tropical and warm-temperate areas but is either absent in very dry regions or poorly represented in regions with periodic drought. It grows terrestrially in more or less shaded locations, from sea-level up to high in the mountains, less often in open places, on all kinds of soils. Garden ornamentals have become established far outside their natural ranges. P. cretica is found on mountain slopes and forests. P. ensiformis is not uncommon and is mostly found in shady places under rocks, in crevices, or old, wet walls. P. semipinnata occurs in lightly shaded locations in the lowlands, not in heavily shaded forest. P. vittata is a common fern of the lowlands, in open sunny sites, sometimes on walls, varying much in size. Other species of the genus are common in primary and secondary vegetation. P. vittata grows in central Florida (United States) on soils contaminated with up to 1600 ppm chromated copper arsenate, whereas in Thailand it has been found on mine tailings with As concentrations of up to 15 600 ppm, and transplanted plants survived on contaminated soil from Hunan with 23 400 ppm As. P. melanocaulon Fée of the Philippines does not grow well where soil copper levels are below 300 ppm and becomes more vigorous with higher concentrations. Both species accumulate the contamination in their tissue that end up having higher concentrations of pollution compounds than the soil.

Propagation and planting

All Pteris species grow easily from spores, and this is their preferred method of propagation, although it is possible to propagate from rhizome cuttings and by separation of plantlets. The best germination and rhizoidal and protonemal growth was observed following storage of the spores at 20°C. Spores stored at 20°C contained the highest content of total soluble sugars, free amino acids and total proteins. Fresh spores contained the highest content of amino acids, proteins and sugars. An optimum medium for spore germination and growth of P. ensiformis is Peace River peat, with addition of dolomite at 3-6 kg/m³to the optimum soil pH of 4.8-5.8, with 300-400 ppm soluble salts and optimum light intensity 4450 lux.

The sporophyte production can be enhanced by transplanting the three-month-old sporophytes grown on Murashige and Skoog solid medium to a medium supplemented with benzyladenine acid (4.4 μm). After a month the rhizomes become swollen with multiple growth centres. Homogenized and plated on a hormone-free medium, 1 g of rhizome can give rise to about 1000 sporophytes.

If planted in gardens, the soil should be poor and well drained for all Pteris species. P. ensiformis and P. semipinnata prefer wet, shady conditions while other species may also grow in more sunny sites.

Husbandry

Pteris is mainly cultivated for ornamental use while leaves and rhizomes are collected from the wild for other uses. Experimental trials have been carried out with the aim of evaluating P. tremula for cut foliage production. Under the climatic conditions of the Riviera Liguriari (Italy) it can be grown in a greenhouse with a maximum irradiance level of 25 000 lux in summer. The plants were grown in a 30 cm organic substrate layer, composed of an equal mixture of fallen beech leaves and peat moss.

Diseases and pests

In India the mould Colletotrichum gloeosporioides ( Glomerella cingulata ) has been recorded on P. vittata , and the pentatomid Coptosoma siamica as a pest of P. quadriaurata above 1400 m altitude. The nematode Aphelenchoides fragariae sometimes heavily infects Pteris species. Soil drenches with the nematicides aldicarb or methomyl, as well as nemagon used as a preventive dressing on young plants, resulted in improved growth and absence of nematodes 10 weeks after treatment.

Harvesting

Pteris plants grown from spores are large enough to produce leaves for ornamental use after 1 year.

Yield

In Italy, the annual yield of leaves of P. tremula with a length of 40 cm was 336 leaves per m²at a density of 11.1 plants per m²and 364 leaves at a density of 16.7 plants. Yield was high in spring and summer but a minimum yield of nearly 1 leaf per plant per month was obtained in January at a minimum temperature of 8°C.

Handling after harvest

Minimum vase life of P. tremula was 15 days, even after dry storage at 18°C and 90-95% relative humidity for 3 days, or after dry storage at 5°C for 5 days.

Genetic resources

Germplasm collections of Pteris are numerous, particularly where commercial breeding activities for new ornamental cultivars exist.

Breeding

Pteris has the greatest range of morphological features of any fern genus. Many species hybridize easily and several of these hybrids are sexually fertile, or have become so, after polyploidisation, or can be propagated asexually. Although some Pteris species have been cultivated for over 200 years, relatively few new forms have arisen that could be propagated as cultivars. With P. ensiformis though, some successful variegated cultivars have been produced. The variegated character is due to a dominant gene. However, in the true-breeding of apogamous species, breeding is directed towards creating superior strains by hybridization or by selection from the wild.

Prospects

In Indonesia, Malaysia, the Philippines and Papua New Guinea, only the use of Pteris as an ornamental is common. Their effectiveness as medicines and the active substances are being investigated with promising results. Pteris is well known for the occurrence of hybrids and apogamous species that may contribute to their success in commercial cultivation as ornamental plants.

At present, P. vittata is a focus of interest as a potential agent for phytoremediation of arsenic contaminated soils. Phytoremediation is the process of employing plants to decontaminate soils by utilising their ability to accumulate certain soil compounds. Phytoextraction attempts to remove contaminants from the rhizosphere through plant uptake and accumulation in roots, leaves or stems. The plants are then harvested and the contaminants reclaimed from the plant biomass or the plants are disposed of at a waste facility. Its ability to grow on arsenic-contaminated sites and to accumulate the pollutant make P. vittata a most promising candidate. However, the practicability of using it to clean soils under field conditions has yet to be proven.

Literature

Farina, E., Paterniani, T., Mascarello, C. & Robaldo, G., 1996. Agronomic evaluation of Pteris tremula for cut foliage production. Colture Protette 25(2): 101-104 (in Italian, with English summary).
Kobayashi, A., Egawa, H. & Koshimizu, K., 1975. Antimicrobial constituents in Pteris inaequalis Bak. Agricultural and Biological Chemistry 39(9): 1851-1856.
Li, J.H., He, C.W., Liang, N.C., Mo, L.E. & Zhang, X., 1999. Effects of antitumor compounds isolated from Pteris semipinnata L. on DNA topoisomerases and cell cycle of HL 60 cells. Acta Pharmacologica Sinica 20(6): 541-545.
Li, J.H., Liang, N.C., Mo, L.E., Zhang, X. & He, C.W., 1998. Comparison of the cytotoxicity of five constituents from Pteris semipinnata L. in vitro and the analysis of their structure activity relationships. Yaoxue Xuebao 33(9): 641-644 (in Chinese, with summary in English).
Lu, H., Hu, J., Zhang, L.X. & Tan, R.X., 1999. Bioactive constituents from Pteris multifida. Planta Medica 65: 586-587.
Ma, L.Q., Komar, K.M., Tu, C. , Zhang, W., Cai, Y. & Kennely, E.D. , 2001. A fern that hyperaccumulates arsenic. Nature 409: 579.
Okuno, M., Kameoka, H., Yamashita, M. & Miyazawa, M., 1993. Components of volatile oil from plants of Polypodiaceae. Journal of the Japan Oil Chemists' Society 42(1): 44-48 (in Japanese, with summary in English).
Raymundo, A.K., Tan, B.C. & Asuncion, A.C., 1989. Antimicrobial activities of some Philippine cryptogams. Philippine Journal of Science 118(11): 59-75.
Siman, S.E., Povey, A.C., Ward, T.H., Margison, G.P. & Sheffield, E., 2000. Fern spore extracts can damage DNA. British Journal of Cancer 83(1): 69-73.
Walker, T.G., Ide, J.M., Jermy, A.C. & Paul, A.M., 1992. The genus Pteris, its breeding systems and its horticultural potential. In: Fern horticulture: past, present and future perspectives. Proceedings of the International Symposium on Cultivation and Propagation of Pteridophytes, London, 7-11 July 1991. The British Pteridological Society, Intercept, Andover, United Kingdom. pp. 195-207.

Authors

H. Schneider & G. Rusea