<<Disclaimer: Verify this information before applying it to your situation.>>

Seeing as how the cassava root is the source of Tapioca, my educated (but
not perfect) guess is that the cassava is indeed gluten free.  It is a
tuberous root, from which tapioca products are made.

We use tapioca starch, which is gluten free, with great success.
Have fun!

Bob at Ultimate Baking

Great Gluten Free Biscotti,
GF All Purpose Flour Mix and GF Heavenly Chocolate Cake Mix
 www.ultimatebiscotti.com