What starchy substance makes up the chewy bits nestled at the bottom of the trendy bar smoothie called “boba”

http://en.wikipedia.org/wiki/Tapioca

These are not seeds, but rather reconstituted processed root of the tapioca (bitter-cassava) plant.

These tapioca pearls are made mostly of tapioca starch.

In other parts of the world, the bitter-cassava plant may be called “manioca” or “yuca”.