Sassafras the Source of "File" Used in Gumbo?

On page 66 of your 1998 catalogue, under number 5285, you list SASSAFRAS (Sassafras albidum).
Would I be right in thinking that the leaves of this species of sassafras are the source of "Fil?", that thickening agent used in the traditional gumbos of the Deep South (see : www.aliceville.com/cookglos.htm#sectF).
I've been looking for a Canadian supplier of "file" for a long time, but to no end. I'm now thinking of growing my own. All I need is the right tree. Would this be the one ?

Dr. James Duke, in his book "Handbook of Medicinal Plants", says that sassafras is indeed the file of gumbo in Creole cooking.
Sassafras is considered toxic and you are cautioned to read more about the use of the plant for cooking. On one hand, it has long been used for cooking and in various beverages, but the U.S. and Canadian governments both insist that the plant should not be used internally. It is considered a "low grade" liver carcinogen. Duke, himself, however, says that he wouldn't hesitate to drink sassafras, rating it as about as dangerous as two cups of coffee day.