The classic Martin Herringbone pattern as used in their purfling is generally made of holly and either ebonized maple or East Indian Rosewood, though a host of others may be used. It must have "bendability" and these woods, though quite hard, work very well together. Most of the newer ones are "assembled" (the strips) with newer glues that allow bending in boiling water as opposed to the traditional bending iron or steam methods. Herringbone is generally used only as purfling or backstrips and the strips are formally called "intarsia." when you inlay the strip, it's known as marquetry.

Various forms of purling are available in patterns and in solid woods and plastics although on fancier stuff, abalone and pearl are still widely used for this decorative touch. You can make a minor case that the purfling groove provides a finished end to the top and thus in combination with bindings can reduce the chance for cracking............but let's face it.....it's really decoration!

The Herringbone pattern is mostly associated with the Martin D-28, although I have no idea when Martin first used the style. Purfling existed for mucho many years prior to that obviously.

Taht's about the limit of my brain on the subject. Hope it helps!

Spaw