The Polynesians brought this plant with them to Hawaii. It has roundish white underground tubers which are full of starch. It was the tuber that the Hawaiians used for medicine.

The tubers were grated and the grated material put in water in a calabash -- the starch settled on the bottom. Each day, for several days, the clear water was poured off and fresh water was added -- this was to get rid of a bitterness in the pia starch. When all the bitterness was gone, the last water was poured off, and the starch was spread on a flat stone to dry. When it had dried as a sheet of starch, it was scraped off, and ground up into a powder in a stone mortar with a stone pestle.

This dry, raw starch was used to cure diarrhea and dysentery.