Q From Hans: Why do we call it a briar pipe when it has nothing to do with briars?
A This is a classic case of folk etymology, in which English people have heard an unfamiliar word from another language, in this case French, and turned it into one that sounded more sensible to their ears.
The wood from which briar (or brier) pipes are made is actually a type of heather, the white heath, which grows in the south of France as well as in other parts of the Mediterranean coast. The pipes are carved from the root. In French, this plant is called bruyer, which is from bruyère, heath.
When the wood was introduced into Britain in the 1860s, its French name was quickly changed because people confused it with the native word that referred either to the bramble or the wild rose.