Didymocarpus sulphureus

I never knew this genus before I saw it during my trip in Malaysia, since I did not expect to see this plant in our itinerary.  On our way down to Brinchang town from the mossy forest, the van moved slowly due to it's a mountain route, so I looked outside along the road to see if there was something interesting.  I randomly saw few yellow flowers swaying in the wind.  I was not sure what it is, so I asked the driver to park at roadside for few minutes, then I got off to check it closely. I took some photos first and thought it should belong to Gesneriad family by instinct.  When I came back to Taiwan, I tried to identify the ID of this plant and luckily I found it in the flora of Malaysia. The plant I saw is "Didymocarpus sulphureus" and that's all that I know, not any else information about it.