Notes on fairy orchids ( Magnoliopsida : Asparagales : Orchidaceae : Oberonia ) of Sri Lanka : revision in regional distribution and documentation on vegetative propagation

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The genus Oberonia Lindley was first described by Lindley in 1830 [Lindley 1963[Lindley (1830))], after 'Oberon' the mythological king of fairies.At the beginning Lindley described 13 Oberonia species and subsequently many species were recognized and are still being described.According to Pridgeon et al. (2006) the genus consists of 150-200 species but based on the latest updates, this genus consists of 343 accepted species (eMonocot 2015).
Similarly, Oberonia longibracteata is another species that has been recorded as endemic to Sri Lanka by the Handbook to the Flora of Ceylon (Trimen 1893), the Revised Handbook to the Flora of Ceylon (Jayaweera 1981), an annotated check list of Orchids of Sri Lanka (Fernando & Ormerod 2008), and the national red list of threatened flora and fauna of Sri Lanka (MOE 2012).Contradictory to these reports, O. longibracteata has been recorded from India (Kerala), Thailand, Cambodia, China and Vietnam (Ansari & Balakrishnan 1990;Pridgeon et al. 2006;eFloras 2008;Averyanov 2013).It is recorded as a well-known folk medicine for scorpion bites in Cambodia (Lewis & Elvin-Lewis 2003;Pridgeon et al. 2006).
This record once again reduces the number of endemic Oberonia species in Sri Lanka to eight (including Oberonia meegaskumbura) and the total number of endemics in the family Orchidaceae remain at 50 with the addition of the recently recognized endemics, O. meegaskumbura and Podochilus warnagalensis Wijewardana, Priyadarshana, Arangala, Attanagoda, Samarakoon & Kumar (Wijewardana et al. 2016).The accurate status of a species is important for the validity of the other documentation such as taxonomic revisions and evaluation of the conservation categories during the red listing and the richness of the biodiversity of the island.
Sexual reproduction is commonly observed in the family Orchidaceae.However, vegetative propagation by the means of producing adventitious buds with roots towards the ends of stems/leaves is also recorded in few genera such as Podochilus Blume (1825), Vanda Jones ex R. Br. (1820), and Phalaenopsis Blume (1825).According to the available literature, the reproduction of species belonging to the genus Oberonia was exclusively sexual, via seeds (Jones et al. 2010 who referred to (Clements 1989;Dockrill 1969Dockrill , 1992;;Schlechter 1911Schlechter , 1982;;Seidenfaden 1978)), until an observation was made in 2013 by Averyanov on vegetative propagation by means of producing new plantlets from the axils of floral bracts of old inflorescence in Oberonia longibracteata.In the present communication we record a recent observation, on vegetative propagation of the same species, O. longibracteata, and this will be the first record of vegetative propagation of an Oberonia species in Sri Lanka.This observation was made at Hantane Forest Reserve at an elevation of 1,203m during the dry season in Kandy District, Sri Lanka (Image 1).These propagules were observed, emerging at a distance of about ½ to ⅔ from the base of the fleshy matured leaves where the drying inflorescence is attached.These newly emerged keikis have the ability to grow into a mature plant while being attached to the mother plant and also produce flowers and fruits.Once this leaf bearing the keiki dries off, the keiki starts growing as an independent plant by gradually attaching to the nearby surface.As this observation was made during the dry season in November, this could be an adaptation to survive and reproduce.This mechanism ensures the reproductive success and survival of the species during exhausting environmental conditions by producing fully grown propagules.

Image 1 .
Oberonia longibracteata Lindl.A -a small population of plants growing as lithophytes cling to the surface of rocks; B -a mother plant with vegetatively propagated plantlets bearing flowers/ dried seeds/ fresh seeds circled in yellow.© W.A.M.P. Ariyarathne A B