In a barber shop quartet, a tenor sings the melody, a countertenor sings above and a baritone and bass sing below. Wine blends create harmonies in similar ways.

Wines blended from two or more grapes are among the world’s best and most expensive. They range from traditional ones with centuries-old formulas to freewheeling blends that occasionally even mix white grapes among the reds.

At the traditional end, France’s red Bordeaux are blends of at least two of the following grapes: cabernet sauvignon for structure and rich berry flavors, merlot for smoothness, cabernet franc for aromas of flowers and earth, malbec for inky violet hue and petit verdot for spice.

Since Bordeaux’s red wines, with their five-grape recipe, are the world standard, a group of American vintners in 1988 formed the Meritage Association to make wines here to that formula, and today they produce some of America’s top wines.

California’s Rodney Strong Vineyards 2009 “Symmetry” Red Meritage from Alexander Valley is made up of cabernet sauvignon, malbec, merlot and cabernet franc. Continuum Estate’s 2009 red wine, made by children of Robert Mondavi, has cabernet sauvignon, cabernet franc, petit verdot and merlot.

Other American winemakers are experimenting with ever-more audacious blends. There are rules. In California, a wine must have 75 percent of one grape variety to be called by that name. Still, it leaves some room for tinkering.

For example, Murphy Goode’s 2010 Pinot Noir is 86 percent pinot noir, with 14 percent syrah added for structure. Mettler Family Vineyards’ 2009 Estate Grown “Old Vine” Zinfandel is 78 percent American-style zinfandel plus French Rhone Valley-style petite sirah and French Bordeaux-style cabernet sauvignon and cabernet franc.

Some wineries take this to great lengths. Kendall-Jackson’s “Vintner’s Reserve” Syrah includes red syrah, zinfandel and petite sirah grapes plus two whites, chardonnay and viognier, for sweet softness and fruit.

Finally, if you want to be pedantic, Meritage isn’t pronounced meri- taaghe in the French way. It’s a combination of “merit” and “heritage,” and it rhymes with the latter. That should boost your street cred with your snooty wine friends.

Highly recommended

•  2009 Rodney Strong “Symmetry” Meritage Red Wine, Alexander Valley (79 percent cabernet sauvignon, 14 percent malbec, 6 percent merlot, 1 percent cabernet franc): sweet blackberry and spice aromas, flavors of blackberries and bittersweet chocolate, very smooth, opulent; $55.

•  2009 Mettler Family Vineyards Estate Grown “Old Vine” Zinfandel, Lodi (78 percent zinfandel, 12 percent petite sirah, 8 percent cabernet sauvignon, 2 percent cabernet franc): rich aromas and flavors of red plums, sweet chocolate and spice; $20.

•  2009 Continuum Estate, Napa Valley (77 percent cabernet sauvignon, 12 percent cabernet franc, 7 percent petit verdot, 4 percent merlot): powerful and lush, with intense flavors of black cherries, cloves and chocolate, smooth, long finish; $165.

Recommended

•  2010 Echelon Cabernet Sauvignon, Alexander Valley (100 percent cabernet sauvignon): aroma and flavor of black cherries and black coffee, smooth and rich; $18.

•  2010 Kendall-Jackson “Vintner’s Reserve” Syrah, Santa Barbara County (98.6 percent syrah, 0.6 percent chardonnay, 0.4 percent viognier, 0.3 percent zinfandel, 0.1 percent petite sirah): aromas and flavors of black cherries, mocha and spice, smooth; $17.

•  2010 Murphy-Goode Pinot Noir, California (86 percent pinot noir, 14 percent syrah): aromas and flavors of black plums and cloves, soft tannins; $15.

•  2010 Round Pond Cabernet Sauvignon, Napa Valley (100 percent cabernet sauvignon): floral aromas, flavors of black cherries and mocha, long and smooth; $30.

•  2008 Gallo “Signature Series” Cabernet Sauvignon, Napa Valley 86 percent cabernet sauvignon, 8 percent petit verdot, 6 percent petite sirah): hint of oak, aromas and flavors of black cherries and dark chocolate; $40.

•  2010 Bridlewood Estate Central Coast Blend 175 (syrah, merlot, tempranillo, cabernet sauvignon): black raspberry, milk chocolate and spice aromas and flavors; $15.