noun
or briarroot ˈ ̷ ̷ˌ ̷ ̷
Etymology: brier (II) , briar + root
: the root of various plants (as Erica arborea of southern Europe or members of the genera Rhododendron and Smilax of the United States) used in the manufacture of tobacco pipes ; especially : the burl of the brier used in the manufacture of briars