Intermediate grower from Myanamar, Vietnam, Lower Thailand, Malaysia, Sumatra, Borneo and Sulawesi. This is probably the white variety, another one has a red spot in the throat. My first time dealing with it. It's just beginning to bloom and the leaves are already turning yellow, see bottom right of picture. Apparently the leaves will fall off as the plant gets further into it's blooming cycle. When it finishes booming one is supposed to repot it, give it a dry winter and then wait for new growth to appear.

Nick