Platycerium bifurcatum (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Platycerium bifurcatum (Cav.) C. Chr.

Protologue: Index filic.: 496 (1906).

Family: Polypodiaceae

Chromosome number: 2n= 74 (subsp.bifurcatum)

Synonyms

Platycerium willinckii T. Moore (1875), P. hillii T. Moore (1878), Alcicornium veitchii Underw. (1905).

Vernacular names

• Staghorn fern, elkhorn fern (En)
• Indonesia: paku uncal (Sundanese), simbar agung (West Kalimantan), simbar menjangan (Javanese, Balinese)
• Philippines: dapong repolyo (Tagalog).

Origin and geographic distribution

P. bifurcatum , in the wide sense used here, is found from Java, through the Lesser Sunda Islands and New Guinea to eastern Australia. As an ornamental it is cultivated all over the world.

Uses

P. bifurcatum is a valuable ornamental. The leaves were used as poultice to treat fevers in the belly. In Java, the leaves were ground with Foeniculum vulgare Miller (fennel, "adas"), Alyxia reinwardtii Blume ("pulasari") and red onion and applied to swellings.

Production and international trade

There is high demand for P. bifurcatum as an ornamental species in Europe, Australia and the United States, and as a result there is large scale production of the plant in these areas.

Description

Epiphytic fern with fleshy, repeatedly forked foliage leaves and round base leaves, appressed to the substratum. Rhizome short, hidden, with basally attached or peltate scales; scales 1.5-11 mm × 0.3-1.3 mm. Leaves dimorphic, closely clustered; sterile base leaves sessile, not articulated to the rhizome, withering soon but long persistent, erect or appressed, 18-60 cm × 8-45 cm, the apical margin entire to lobed, greyish-green but soon turning brown; fertile and sterile foliage leaves ascending to pendulous, articulated to the rhizome, 0.25-1 m long, the base narrowly wedge-shaped, margins entire, apex 2-5 times bifurcate, the first fork usually occurring at or below the middle of the leaf, one division often remaining undivided following the forking of the leaf, the latter thus appearing to divide in three, the upper surface green, sparsely to densely covered with stellate hairs, the lower surface greyish-green, densely covered with stellate hairs; ultimate divisions elongate, commonly 0.5-2.5 cm broad, sometimes wider. Sporangia in 1-10 soral patches, borne over the greater part of the lower surface of the ultimate segments of the fertile leaves, sometimes reaching around the sinus of the first fork, sometimes not reaching the apex, with shortly stalked paraphyses.

Other botanical information

Platycerium Desv. comprises about 15 species, 6 in Africa, 8 in Asia, 1 in South America. In Malesia 6 species are found. Platycerium is closely related to Pyrrosia Mirbel with which it forms a monophyletic group.

In P. bifurcatum 3 subspecies are distinguished:

• subsp. bifurcatum : rhizome scales up to 11 mm long, base leaves up to 50 cm long, foliage leaves erect, spreading or pendulous. Within this subspecies, two varieties are distinguished:

• var. bifurcatum : upper part of the base leaves more or less sinuate, foliage leaves mostly spreading, asymmetrical, densely hairy; occurring in eastern Australia;

• var. hillii T. Moore: upper margin of the base leaves entire, foliage leaves erect, more or less symmetrical, sparsely hairy; occurring in New Guinea and eastern Australia.

• subsp. veitchii Underw.: occurring in eastern Australia.

• subsp. willinckii T. Moore: rhizome scales short, up to 5 mm long, base leaves up to 70 cm long with lobed upper margins, foliage leaves pendulous; occurring in Java and the lesser Sunda Islands.

All these infraspecific taxa have often been treated as different species, but in cultivation they easily hybridize, producing many different intermediate forms.

P. coronarium (König ex Müller) Desv. is a species with long, pendulous foliage leaves, reniform fertile lobes and base leaves with a deeply lobed upper part. It is found in Indo-China, Peninsular Malaysia, Sumatra, Java, Borneo and the Philippines and was used in Malaysia to enlarge the spleen by rubbing the ashes over the body. It is also commonly cultivated in gardens in South-East Asia.

Ecology

P. bifurcatum grows as an epiphyte in various kinds of forest and open vegetation. Locally it can be the dominant epiphytic species. It is found from sea-level up to 2000 m altitude. It is well adapted to dry conditions. The base leaves of Platycerium form a receptacle for litter, which develops into a peat-like substance that is both moist and well drained. The host sometimes produces aerial roots in this substrate.

Propagation and planting

P. bifurcatum can be easily grown from spores. Mature plants develop additional growth centres ("pups") which can be severed and planted apart. Mass propagation is done by tissue culture or gametophyte production on agar. Optimal growth of gametophytes can be obtained on modified Miller medium supplemented with 4% sucrose, 0-0.6% agar and the pH adjusted to 5.5.

Husbandry

Platycerium is very drought resistant and easily overwatered, which causes the roots to rot. The plants must be rooted in a well-aerated growing medium, or attached to a tree trunk or mounted on a piece of wood.

Genetic resources and breeding

Germplasm collections of P. bifurcatum are not known to exist. Many breeding programmes for P. bifurcatum exist and numerous ornamental cultivars have been released.

Prospects

P. bifurcatum is an important ornamental, suitable for a wide range of ecological conditions, including the artificially heated indoor environment. No decline of its popularity is foreseen at present. Other species of Platycerium gradually penetrating the market do not seem to be competitors yet. Little is known about the medicinal properties of P. bifurcatum and further research into this field should be encouraged.

Literature

• Camloh, M. & Gogala, N., 1992. In vitro culture of Platycerium bifurcatum gametophytes. Scientia Horticulturae (Amsterdam) 51(3-4): 343-346.
• Hennipman, E. & Roos, M.C., 1982. A monograph of the fern genus Platycerium (Polypodiaceae). North-Holland Publishing Company, Amsterdam, The Netherlands. 126 pp.
• Hennipman, E. & Roos, M.C., 1998. Platycerium. In: Kalkman, C. & Nooteboom, H.P. (Editors): Flora Malesiana. Series 2. Pteridophyta. Ferns and fern allies. Vol. 3. Rijksherbarium/Hortus Botanicus (under the auspices of Foundation Flora Malesiana), Leiden, The Netherlands. pp. 133-143.
• Herbert, D.A., 1958. Natural air-layering in humus-collecting epiphytes. Queensland Naturalist 16(1/2): 22-23.
• Vail, R., 1989. Platycerium hobbyist's handbook. 4th Printing. Desert Biological Publications, Las Cruces, New Mexico, United States. 171 pp.

Authors

Dedy Darnaedi & Titien Ngatinem Praptosuwiryo