A reply from Dan Mathew
Dear Dr
These are not Curcuma neilgherrensis, since they dont have sterile bracts (coma)
at the tip of the spike.
The white flowered one is Curcuma oligantha which has distribution only in northern Kerala and South Karnataka in India, also in Sri Lanka.
The yellow flowered one is its endemic variety: Curcuma oligantha var. lutea.
Dr. Mathew Dan
TBGRI, Plaode