Pinot Meunier, like Pinot Blanc and Pinot Gris, is one of the many mutations of Pinot Noir. The name comes from the appearance of its leaf undersides, which look as though they've been dusted with flour (meunier is French for "miller"). It is also simply called Meunier in France. In Germany, it is known as Müllerrebe (miller grape) and also Schwarzriesling.
The home turf for Meunier is the region of Champagne. Its value there is due to the fact that it buds later and ripens earlier than Pinot Noir. Pinot Meunier thusly avoid damage from early spring frosts or from coulure and can be more reliably productive than either Pinot Noir or Chardonnay in this regard.