Briar, or Bruyere in French, is a dense Burl found on the roots of the Heath tree (Erica Arborea).  The Heath tree, which actually  looks more like a scraggly bush, is found throughout the dry and hot areas along the Mediterranean coast. 

It is important to note that a Burl “wood growth” is an aberration of the tree’s natural characteristics: roots, trunk, branches, leaves.   To this day, this unique, naturally occurring “growth” is  considered the ultimate Pipe making material.