Grenache ??Syrah ??Mourvedre?blended wines ? commonly?known by the acronym GSM ? are the particular specialty of the southern?Rhone Valley?in France.?Grenache?and?Syrahare key in this part of the world, and are complemented in this instance by the addition of?Mourvedre: an important but slightly less famous inclusion to the blend. GSM wines, which have been readily adopted by the New World, are rich, full bodied and leathery, and are characterized by flavors of dark fruit and spice.