Arrowroot

Arrowroot is a flavorless, gluten-free flour derived from the plant Maranta arundinacea. It's quite similar to tapioca flour and may be used in most recipes in a 1:1 ratio. When used as a thickening agent or as part of a baking mix with other types of starches and flours, arrowroot is a perfect substitute for tapioca flour.

When used as a stand-alone flour, it does not provide the same chewy texture as tapioca. As a result, if your baked-goods recipe asks for tapioca flour as the only starch, arrowroot will not work well until combined with other flours. Arrowroot is available at some places and online.