This is what I found on arrowroot at the epicurious dictionary site.  Does
this sound like it would be paleo?

Patti

arrowroot The starchy product of a tropical tuber of the same name. The
rootstalks are dried and ground into a very fine powder. Arrowroot is used
as a thickening agent for puddings, sauces and other cooked foods, and is
more easily digested than wheat flour. Its thickening power is about twice
that of wheat flour. Arrowroot is absolutely tasteless and becomes clear
when cooked. Unlike cornstarch, it doesn't impart a chalky taste when
undercooked. It should be mixed with a cold liquid before being heated or
added to hot mixtures. Some English and early American cookie recipes call
for arrowroot flour , which is the same product. Arrowroot can be found in
supermarkets, health-food stores and Asian markets.