POP MUSIC REVIEW : Vibrancy in Our Own Back Yard : Music: Linda Ronstadt and Vikki Carr are the headliners at the Bowl. But the passionate mariachi music is a star, too.

Odds are that many Southern California music fans could hum “Oh, Canada.” But how many would even recognize the Mexican national anthem?

That’s the selection that kicked off the Mariachi USA festival starring Vikki Carr and Linda Ronstadt on Sunday at the Hollywood Bowl.

Certainly most among the largely Latino crowd that filled the Bowl were familiar with “Mexicanos, al Grito de Guerra” (“Mexicans, to the Cry of War”), as well as with the mariachi stars who performed in the nearly four-hour concert. But it was striking in this context how little the rest of us know about both this colorfully passionate music and the culture from which it sprang, even though we live right in the middle of it.

Let’s face it, in the currently popular quest for exotic “world music” forms, we embrace styles from Africa, the Middle East or Eastern Europe, while virtually ignoring something equally vibrant in our own back yard. How appropriate that this event took place in a facility that is best known as a home to European classical music.

Two of the four mariachi groups on the bill even poked a little fun at that circumstance, offering expert snippets of a few familiar classical themes. One of those groups, Mariachi Sol de Mexico, poked fun at just about everything--it even broke into a rap spoof at one point and closed its set with leader Jose Hernandez doing a not-bad, but definitely tongue-in-cheek Sinatra imitation on “New York, New York,” complete with a Rockettes kick line from the group’s seven violinists. (What, no heavy metal?)

Mostly, though, the group skewered its own mariachi traditions broadly enough that even the non-Latinos in the crowd got many of the jokes. And, although not all on hand may have appreciated these breaks from tradition (there were some hearty boos when another band leader, Nati Cano, gave bilingual introductions instead of just staying en Espanol ), that humor provided a door for the uninitiated to dance through.

The biggest door for mariachi music was opened three years ago by Ronstadt, with her “Canciones de Mi Padre” album. Once again, Ronstadt showed that she’s no dilettante when it comes to mariachi. Her ever-stronger voice was no more the attraction of her short set than her joyful celebration of her family heritage.

Carr, a bigger star now in Mexico than in the United States, was also in great voice, though her set--well-received as it was--seemed out of place with its glossier pop orientation. But two spirited Ronstadt-Carr duets served as a fine cap for the show.

Still, the evening would have been no less enjoyable without those two star names on the bill. The four featured mariachi orchestras each took a slightly different tack with the rich tradition. San Antonio’s Las Campanas de America opened with a punchy, rough-hewn set that included a medley of Tejas tunes: “Yellow Rose of Texas,” “San Antonio Rose” and “Orange Blossom Special.”

Los Campaneros de Nati Cano followed with a lusher, almost cinematic approach, touching at one point on the music’s Spanish roots with a medley of bullfight music. Sol de Mexico then showed that it is much more than just a spoof, its anti-traditionalist stance not obscuring its accomplished musicianship.

Mariachi Vargas de Tecalitlan--a group that has been in existence since before the turn of the century--also incorporated some parody into its set before backing Ronstadt with rich and rousing arrangements.

Why has mariachi music been so overlooked? Perhaps in some ways it’s too familiar, through old movie cliches and its sometimes patronizing use in the name of California commerce, and thus too easy to write off. Maybe Mariachi USA II, being planned for next year, could change a few more minds.