Spelaeanthus chinii

This is the only species in the genus - found on limestone slopes in peninsula Malaysia. It appears to have a rather limited distribution and hence vulnerble to any habitat disturbances. It has filmsy hairy leaves and has white widely opening flowers borned on a branched panicle.
I found this plant perched on a damp dark limestone wall in Pahang. This appears to be too dark for most competing plants.

Not far from it is a carpet of the curious giant one-leaf Gesneriad, Monophyllea horsfieldii.