This is a fairly commmon relative of African violets and appears to be confined to hills and highlands in Peninsula Malaysia. Like so many local members of this family, it is not well known nor commonly grown although it does has merits - its felty leaves for example, and its yellow flowers which is relatively unusual amongsts local gesneriads.
The genus Henckelia was revived by prominent Asian Gesneriad researchers Anton Weber and B. L. Burt in 1998 to include the bulk of the species formerly grouped under Didymocarpus. One would usually encounter members of this large genus, comprising of about 200 species, during a casual walk in a primary lowland forest around the Malesian region. According to Weber and Burt, Didymocarpus now comprises mostly temperate or highland species which may be periodically dormant - not a common trait for lowland tropical gesneriads here.
The trick for growing this plant successfully is cool climate and high humidity, which is not easy to duplicate at home unless you have a bright bathroom with air-con. I collected some seed pods for trial in the lowland and although germination rate is pretty ok, survival has been dismal.
This population is found growing about 50 metres from a mountain stream under very little shade.
Here's another example from the genus Henckelia