Ophioglossum pendulum (PROSEA)

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Plant Resources of South-East Asia
Introduction
List of species


Ophioglossum pendulum L.


Protologue: Sp. pl. ed. 2: 1518 (1763).
Family: Ophioglossaceae
Chromosome number: n= 120-660 (2n= unknown;Ophioglossum:x= 30, level of ploidy is unknown)

Synonyms

Ophioderma pendula (L.) Presl (1845), Ophioglossum moultonii Copel. (1912), O. falcatum Fowler (1940).

Vernacular names

  • Adder's-tongue fern, hanging adder's-tongue fern, ribbon fern (En)
  • Indonesia: simbar gadang (Javanese), kumpai lubang (Sundanese), daun rambut (Malay, Moluccas); Thailand: teen mue nok khao.

Origin and geographic distribution

O. pendulum is widespread in the Old World tropics, from Madagascar and the Seychelles eastwards throughout tropical Asia, including South-East Asia, tropical Australia to Polynesia and Hawaii. It is quite rare in the Philippines. It has become naturalized in Florida (United States).

Uses

Young leaves of O. pendulum are eaten as a vegetable. In the Moluccas (Indonesia), leaves shredded and mixed with coconut oil are used as an ointment to treat hair. In Mindanao (the Philippines) an infusion of the leaves is used as a cough remedy and the spores are administered to newborn babies to rid them of meconium. O. pendulum is also grown as an ornamental.

Production and international trade

O. pendulum is collected from the wild. No international trade exists and it is not in commercial cultivation.

Properties

The ribbon-like, fleshy leaves of O. pendulum are tough and stringy when broken and they taste sweet.

Description

An epiphytic fern with ribbon-like, pendulous leaves and the sporangia in a stalked, spike-like sporophyte. Rhizome small, 1-3 cm long, creeping, fleshy, without scales, bearing many fleshy roots and a few leaves. Leaves 1-6 clustered, pendulous, linear, often one or more times furcate, 0.3-1.5(-4) m × 1-7(-9) cm, base narrowed gradually to a fleshy terete petiole of indefinite length, margin entire and slightly bent backwards, apex obtuse, limp, fleshy or coriaceous; veins forming a series of long narrow areoles, formed by slender oblique cross-veins connecting a series of more or less straight longitudinal veins, the longitudinal veins near the middle of the leaf blade thicker than those near the margin, no midrib beyond the attachment of the spike. Strobilus spike-like on a stalk 0.5-10 cm long, attached near the base of the leaf blade, cylindrical, 2-45 cm × 5 mm, simple, bearing two rows of sporangia which are almost completely fused; sporangia opening by a transverse slit, releasing numerous creamy white spores. Spores globose, trilete, about 50 μm in diameter, finely irregularly rugose.

Growth and development

The tuberous non-green prothalli of O. pendulum are subterranean saprophytes and dependent on a mycorrhizal fungus. The apices are white, the lower parts greyish, yellowish, or brownish. The prothalli are long-lived perennials of indeterminate growth and each may give rise to one or several sporophytes. The completion of the life cycle may take several years. Experiments with the related fern genus Botrychium Sw. suggest that the gametophytes can develop a sporophyte when grown in an axenic (sterile) culture-medium with additional sugar.

Other botanical information

The Ophioglossaceae is the most isolated family of the ferns and some authors consider it more closely related to a lineage of progymnosperms or cycadophytes than to typical modern ferns. Evidence from fossils to back up speculations, however, is lacking. The sporophore is unique and not found in other fern families. O. pendulum belongs to subgenus Ophioderma (Blume) Clausen of the genus Ophioglossum L. which is considered by some to be a separate genus, differing from Ophioglossum by the stalk of the spike clearly adnate to the leaf, no clear separation between stalk of spike and spike and a fertile spike apex. If Ophioderma is considered a separate genus the correct name for the species is Ophioderma pendula (L.) Presl. O. pendulum is a rather variable species, and based on differences in leaf form and habit (e.g. leaves more falcate, pendulous or not, venation visible or not, dwarf habit), several forms, varieties or species have been distinguished. However, because many intermediates exist these distinctions are without practical value and fall within the wide variability, not deserving separate naming.

Ecology

O. pendulum is a pendulous epiphyte on palms (particularly oil palm and sago palm because of the long persisting leaf bases), tree ferns and trees, sometimes indirectly by growing among the roots, leaves and humic nests of other epiphytic ferns such as Asplenium nidus L. or Platycerium coronarium (Koenig) Desv., sometimes on rocks, in the lowlands and hills. When they grow abundantly they may eventually deplete water and nutrients from the nest to such an extent that the hosting fern dies. Old nests of dying or dead Platycerium coronarium with vigorous bunches of O. pendulum used to be quite common in Malesia. O. pendulum normally grows in the shade under humid conditions. Plants from exposed sites have narrower and more branched leaves whereas plants from higher altitudes have broader and shorter leaves than those from the lowland.

Propagation and planting

O. pendulum can be propagated by spores and by rhizome parts. Plants collected from the wild may be grown as epiphytes on palm trunks or in hanging pots and baskets. O. pendulum can be raised in pots like orchids or on dead or living tree trunks, on a soil medium of fern roots, sphagnum moss or coconut fibres. Although partial shading is generally required, the plants must be kept warm and damp at all times.

Diseases and pests

Natural stands of O. pendulum do not show signs of any serious disease or pest. However, bacteria may cause leaf deformations and rotting, and insects may cause some damage as well.

Harvesting

O. pendulum plants grown from spores can be harvested when 2-3 years old. When grown from plantlets taken from the wild, harvesting of leaves may start 6 months after planting.

Genetic resources and breeding

O. pendulum is quite common and widespread and seems not to be liable to genetic erosion. Intraspecific genetic diversity within the Ophioglossaceae has proven to be remarkably low, probably due to self-fertilization of the subterraneous gametophytes. Germplasm collections or breeding programmes are not known to exist.

Prospects

Since O. pendulum can easily be grown on oil-palm trunks there is a potential to increase the production of young leaves as a vegetable. The combined cultivation of O. pendulum and oil palm in existing plantations improves the productivity of the land and increases product diversity. Therefore, the development of plants producing numerous young leaves of a high nutritional value should be taken into consideration.

Literature

  • Amoroso, V.B., 1989. Some economic eusporangiate ferns in Mindanao, Philippines. CMU (Central Mindanao University) Journal of Science 2(2): 2-18.
  • Campbell, D.H., 1911. The Eusporangiatae, the comparative morphology of the Ophioglossaceae and Marattiaceae. Carnegie Institution of Washington, Washington, DC, United States. 229 pp.
  • Holttum, R.E., 1966. A revised flora of Malaya. 2nd edition. Vol. 2. Ferns of Malaya. Government Printing Office, Singapore. p. 40.
  • Johnson, A., 1959. A student's guide to the ferns of Singapore Island. The Malayan Nature Journal 13: 124.
  • Piggott, A.G., 1988. Ferns of Malaysia in colour. Tropical Press, Kuala Lumpur, Malaysia. p. 29.
  • Shieh, W.-C. & Devol, C.E., 1994. Ophioglossaceae. In: Huang, T.-C. (General Editor): Flora of Taiwan. 2nd Edition. Vol. 1. Pteridophyta and Gymnospermae. Editorial Committee of the Flora of Taiwan, Taipei, Taiwan. pp. 63-73.
  • 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. 37-38.
  • Wieffering, J.H., 1964. A preliminary revision of the Indo-Pacific species of Ophioglossum (Ophioglossaceae). Blumea 12: 321-337.
  • Zamora, P.M. & Co, L., 1986. Guide to Philippine flora and fauna. Vol. 2. Economic ferns, endemic ferns, gymnosperms. Natural Resources Management Center, Ministry of Natural Resources and University of the Philippines, Goodwill Bookstore, Manila, The Philippines. pp. 17-18.

Authors

H.C. Ong & Norma O. Aguilar