Dipteris conjugata (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Dipteris conjugata Reinw.

Protologue: Syll. pl. 2: 3 (1825-1826).

Family: Dipteridaceae

Chromosome number: 2n= 66

Synonyms

Polypodium horsfieldii R. Br. (1828), Phymatodes conjugata (Reinw.) C. Presl (1836), Dipteris horsfieldii (R. Br.) Bedd. (1869).

Vernacular names

• Indonesia: paku payung (Indonesian), pitagar payung (Kedayan Dayak)
• Malaysia: bua chek (Malay), shûang shàu ch’uèh (Chinese)
• Philippines: pakong payong
• Thailand: bua chaek (peninsular).

Origin and geographic distribution

D. conjugata is found from Thailand through Indo-China, southern China, Taiwan, Malaysia, Indonesia, the Philippines to New Caledonia and Australia.

Uses

In the highlands of Mindanao (the Philippines), the large leaves of D. conjugata are used as an umbrella. In southern Thailand, the roots of D. conjugata are of medicinal value and often collected.

Production and international trade

D. conjugata is not traded internationally, nor is it commercially cultivated.

Description

A terrestrial, umbrella-shaped fern, 0.5-2 m tall. Rhizome wide- or long-creeping, up to 1.5 cm in diameter, densely setose; setae 0.2 mm × 4-5 mm, lustrous reddish-brown to black, the base sometimes widened. Leaves monomorphous, repeatedly bifid; petiole stout, up to over 2.5 m long, yellow-brown, basally setose; lamina reniform, up to 25-50 cm × 70 cm, divided to the base into two spreading flabellate halves, the base cordate to hastate, apex rounded, coriaceous, glabrous, dark green adaxially, paler or glaucous abaxially, young leaves yellow-green with reddish tinge; segments broadly obovate, up to over 60 cm long, usually twisted through 90 degrees, spreading more or less horizontally, 3 or more times dichotomously divided; ultimate lobes narrowly subtriangular, the margins irregularly and broadly dentate, gradually narrowing into a caudate-acuminate apex; main veins repeatedly dichotomous, intermediate veins forming a dense network with free included veinlets in the areoles. Sori small, numerous, irregular in shape and size, scattered over the undersurface and borne on the minor veins, without indusium, paraphyses capitate. Spores monolete, ellipsoid, 29-38 μm, smooth.

Growth and development

The gametophyte of D. conjugata is naked, cordate-thalloid with thick midrib, slowly growing, eventually elongating, bearing gametangia on the ventral and often also on the dorsal side. The antheridium is of a primitive, massive type with few sperms. The archegonium is also primitive and has a long, straight neck.

Other botanical information

Dipteris Reinw. has no close relatives, its family is of considerable antiquity from the Mesozoic Triassic. It had a worldwide distribution formerly but in its present area it is a relict. It is the only genus of the family, comprising about 8 species in the Old World tropics and subtropics. In taxonomic literature it has often been classified in Polypodiaceae .

Ecology

D. conjugata is common in mountain clearings and on steep banks, generally between 300-2900 m altitude. Some of its localities are on coastal cliffs. It is a specialist of extremely poor edaphic substrates, especially the leached gleyed-clay soils of high mountain ridges and saddles. In forests it is found where sufficient light reaches the forest floor, for example on slopes near waterfalls or in disturbed sites. In East Kalimantan (Indonesia) it is found growing along rivers accompanying Nypa palm in coastal areas. Under disturbed conditions colonies tend to be relatively short-lived, possibly due to competition.

Propagation and planting

D. conjugata can be propagated by spores and by rhizome division.

Husbandry

If D. conjugata is planted, the soil should be acid and well-drained. It likes fairly bright light to light shade and plenty of water. Plants are somewhat difficult to establish, but once growing they are best left undisturbed. Spore germination and vegetative growth are favoured by lower temperatures.

Genetic resources and breeding

Though its distribution pattern is of relic nature and its populations may be or become isolated, D. conjugata is fairly common over a large area and therefore it does not seem to be in danger of extinction. In Australia, however, D. conjugata is among the pteridophytes of conservation interest. Germplasm collections and breeding programmes are not known to exist.

Prospects

The medicinal use of D. conjugata should be investigated and its active compounds identified before its prospects can be reviewed. Research on the ornamental possibilities of D. conjugata is recommended, including the collection of germplasm.

Literature

• Andrews, S.B., 1990. Ferns of Queensland. Queensland Department of Primary Industries, Brisbane, Australia. 427 pp.
• Backer, C.A. & Posthumus, O., 1939. Varenflora voor Java [Fern flora for Java]. 's Lands Plantentuin, Buitenzorg, Dutch East Indies. pp. 244-245.
• Burkill, I.H., 1966. A dictionary of the economic products of the Malay Peninsula. 2nd Edition. Vol. 1. Ministry of Agriculture and Co-operatives, Kuala Lumpur, Malaysia. p. 851.
• Holttum, R.E., 1966. A revised flora of Malaya. 2nd Edition. Vol. 2. Ferns of Malaya. Government Printing Office, Singapore. pp. 135-136.
• Jones, D.L., 1987. Encyclopaedia of ferns. British Museum (Natural History), London, United Kingdom. p. 378.
• Kramer, K.U., 1990. Dipteridaceae. In: Kramer, K.U. & Green, P.S. (Volume editors): Pteridophytes and gymnosperms. In: Kubitzki, K. (Series editor): The families and genera of vascular plants. Vol. 1. Springer-Verlag, Berlin, Germany. pp. 99-101.
• Tagawa, M. & Iwatsuki, K. (Volume editors), 1979-1989. Pteridophytes. In: Smitinand, T., Larsen, K. (Series editors): Flora of Thailand. Vol. 3. Forest Herbarium, Royal Forest Department, Bangkok, Thailand. pp. 481-483.

Authors

Dedy Darnaedi & Titien Ngatinem Praptosuwiryo