Oleandra neriiformis (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Oleandra neriiformis Cavanilles

Protologue: Anal. Hist.Nat. 1: 115 (1799) (" neriformis ").

Family: Oleandraceae

Chromosome number: 2n= 82

Ophiopteris verticillata Reinw. (1824), Oleandra pistillaris (Swartz) C. Chr. (1934), O. colubrina (Blanco) Copel. (1958).

• Indonesia: paku areuy (Sundanese), paku korani (Manado), paku sake (Batak)
• Malaysia: tiaò ch’uèh (Chinese)
• Philippines: kaliskis ahas, lunas (Tagalog)
• Thailand: nakkharat (northern, peninsular), phaya ngu (north-eastern), nakho (Malay, peninsular).

O. neriiformis is widespread in the Asian and Pacific Old World tropics and occurs from northern India and south-western China, throughout South-East Asia to Samoa in the Pacific.

In the Philippines a decoction of the petiole of O. neriiformis is considered an efficacious medicine for alleviating difficult menstruation. A decoction of the rhizome is believed to counteract poisonous snake bites.

Several compounds have been isolated from O. neriiformis : filicene (C₃₀H₅₀), n-octacosanol lignocerate, the 4-desmethyl sterols campestersol, stigmasterol, β-sitosterol and a trace of cholesterol, the 4a-methyl sterols cycloeucalenol, citrostadienol and traces of 24-methylen lophenol, the dimethyl sterols cycloartenol and 24-methylene cycloartenol, the triterpene alcohol nerifoliol, neriifoloxide, a triterpene epoxide (C₃₀H₅₀O) and the triterpene 29-ethoxyhopane (C₃₂H₅₆O). Histochemical tests in the Philippines showed abundant amygdalin and saponin in rhizomes and pinnae, and formic and tartaric acid in aerial stems. The related species O. wallichii (Hook.) C. Presl (occurring from northern India and southern China to Thailand, northern Vietnam and Taiwan) contains the triterpenoids hop-17(21)-ene and neohop-13(18)-ene, which greatly inhibit Epstein-Barr virus activation induced by the tumour promoter 12-O-tetradecanoylphorbol-13-acetate (TPA). Hop-17(21)-ene and neohop-13(18)-ene exhibit remarkable anti-tumour promoting effects against mouse skin tumour promotion in an in-vivo 2-stage carcinogenesis test using 7,12-dimethylbenz[a]anthracene as an initiator and TPA as a promoter.

A terrestrial thicket-forming fern, up to 2 m tall, with a branching shrublike habit, easily mistaken for a flowering plant, sometimes climbing-epiphytic. Rhizome stiff, erect or suberect, up to 10 mm in diameter, acting as an aerial stem, densely covered with scales; scales appressed, imbricating, the peltate basal part 1-1.5 mm wide, dark brown to black, narrowed abruptly into the up to 3.5 mm long apical part which is ciliate when young; aerial stem branched, straight, 1-1.5(-2) m tall, with few or no rhizophores, the leaves close together in pseudowhorls of 4-14, the whorls separated by 2-10 cm long internodes. Leaves simple, clustered, more or less coriaceous, on 2-5 mm long phyllopodia borne on all sides of the aerial stem; petiole 0.5-10 mm long, scaly; lamina oblanceolate, up to 40 cm × 3.5(-7.5) cm but often narrower, base attenuate, margins entire, apex caudate-acuminate, midrib scaly when young, glabrous or pilose; veins close together, simple or once forked, straight, at a broad angle to the midrib. Sori in one irregular row on each side of the midrib, usually 0-3 mm from the midrib; indusium reniform, up to 2 mm wide. Spores monolete, ellipsoid to spheroid, with irregularly toothed wings.

The gametophyte of O. neriiformis is cordate, often hairy, sometimes bearing short-stalked antheridia. When terrestrial the sporophyte has a shrublike habit with erect growth, when growing as an hemi-epiphyte it is straggling.

The taxonomy of the genus Oleandra Cavanilles is confused and various authors have stressed the need for a worldwide revision. For a long time about 40 species were known, but the descriptions were based on too few collections. Tryon revised the genus for the American tropics and reduced the number of species to 4. For Africa he estimated the presence of 5 species and for the Asiatic and Pacific tropics 6 species. Formerly ill-defined species became synonyms of O. neriiformis and, in addition to the ones mentioned above, the following names are also considered synonymous: O. angusta Copel., O. archbaldii Copel., O. bantamense (Blume) Kunze, O. ciliata Kuhn, O. cuspidata Baker, O. herrei Copel., O. hirtella Kunze, O. maquilingensis Copel., O. mollis C. Presl, O. nitida (Copel.) Copel., and many more are mentioned in the literature. Although O. neriiformis is the most abundant and most widespread species of the genus, it does not occur in Australia (records refer to O. musifolia (Blume) Kunze), Africa or South America (records are due to misapplications of the name). O. neriiformis is a very variable species (hence the many names) but overall distinctive characteristics are the similar fertile and sterile leaves and the sori closer to the midrib than to the margin. A distinctive characteristic of the family Oleandraceae is the articulate petiole (often on a phyllopodium, an outgrowth of the stem) in simple leaved species or articulate pinnae in pinnate ones.

O. neriiformis is found from sea-level up to 2200 m altitude but mostly above 1000 m, Usually it forms straggling shrubs to thickets in mountain forest. Sometimes it is found between other epiphytes high in the crowns of mossy trees, occasionally on trunks of palms that retain their leaf bases, but also on rocks or lava.

O. neriiformis is hardly cultivated. Though it is easily propagated by spores, propagation by rhizome cuttings is easier and faster. Rhizome fragments can be grown in pots with sandy loam and a thin layer of humus, but they can also be attached to a tree trunk (e.g. of a tree fern).Young plants grown from spores can be transplanted to pots, logs or tree fern trunks.

Plants of O. neriiformis should be watered every day without getting the soil too wet. Chemical fertilizer can be given once a month, while direct sunlight may damage young plants.

About 2 years after sowing from spores, the rhizomes of O. neriiformis are big enough to be collected for medicinal use. When it is propagated by rhizome cuttings, the harvest will be earlier. After collecting, the rhizomes are cleaned of roots and dust, cut into small pieces, dried and stored until needed. Petioles can be collected any time when needed.

Germplasm collections or breeding programmes are not known to exist for O. neriiformis . Given its great variability, germplasm collection is recommended in order to avoid genetic erosion.

The medicinal properties of O. neriiformis seem interesting because of the available bio-active constituents. Further research may reveal new applications and commercial possibilities. Investigation of the ornamental possibilities of this unique shrubby fern is recommended.

• Goswami, A., Dasgupta, A., Nath, A., Roy, T.K. & Khastgir, H.N., 1979. Reinvestigation on the fern Oleandra nerifolia, Pteridophyta: isolation of a new triterpene 29-ethoxyhopane. Tetrahedron Letters, Oxford, Jan 1979(3): 287-288.
• Holttum, R.E., 1966. A revised flora of Malaya. 2nd Edition. Vol. 2. Ferns of Malaya. Government Printing Office, Singapore. pp. 383-387.
• Konoshima, T., Takasaki, M., Tokuda, H., Masuda, K., Arai, Y., Shiojima, K. & Ageta, H., 1996. Anti-tumor-promoting activities of triterpenoids from ferns 1. Biological and Pharmaceutical Bulletin 19: 962-965.
• Kramer, K.U., 1990. Oleandraceae. 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. 190-193.
• Pandey, G.N. & Mitra, C.R., 1969. Constituents of Oleandra neriifolia. Phytochemistry 8:1607.
• 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. 179-182.
• Tryon, R., 1997. Systematic notes on Oleandra. Rhodora 99: 335-343.
• Tryon, R., 2000. Systematic notes on the Old World fern genus Oleandra. Rhodora 102: 428-438.
• Wan, A.S.C., Aexel, R.T. & Nicholas, H.J., 1972. Sterols and triterpenes of Oleandra pistillaris. Phytochemistry 11: 2882-2883.
• 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. p. 42.

J.J. Afriastini