Production of Sporophytes from Platycerium coronarium and P. ridleyi Frond Strips and Rhizome Pieces Cultured in Vitro

Abstract

Platycerium is a genus of large, attractive epiphytic ferns that mainly grow on trees. In Singapore, two species have been known - P. coronarium (Koenig) Desv. and P. ridleyi Christ. The former commonly grows on forest and undisturbed wayside trees (Wee, 1978) while the latter is rare. P. ridleyi was once collected from tall trees in the primary jungle of Bukit Timah, but it is now thought to be extinct there (Holttum, 1966; Wee, 1984). During the 1970s and 1980s epiphytes were systematically removed from wayside trees in Singapore because it was thought that they contributed to the rotting of host tree branches. It was further thought that P. coronarium encouraged the breeding of mosquitoes (Wee, 1990). However, in 1990 there was a change in government policy. Epiphytes, including P. coronarium, were looked upon with favour, and their presence on wayside trees was encouraged. Efforts were thus made to reintroduce P. coronarium as well as a few other selected epiphytes onto wayside trees to enhance the attractiveness of the Garden City. However, two decades of systematic removal of the fern had resulted in their disappearance from most trees in Singapore (Wee, 1985; Wee & Corlett, 1986). The only source of planting materials was Peninsular Malaysia, where they commonly grow on rubber trees. Unfortunately, the sudden demand outstripped the supply. As for P. ridleyi, the species is extremely rare. Also, it does not produce young plants vegetatively while P. coronarium does so only infrequently. Thus the only source of large numbers of planting materials was propagation by spores or by tissue culture. This paper reports the production of P. coronarium and P. ridleyi sporophytes from stem and frond explants.