A celebration marking a half century since the opening of the seminal Los Angeles folk/blues/world club the Ash Grove brought something home: The roots of American roots music is in rootlessness.

All night long, in the first of two evening concerts marking this milestone, artists who in more recent years shaped modern American roots music -- Ry Cooder, Taj Mahal, Dave Alvin -- reminisced warmly on the stage at UCLA's Royce Hall about teenage journeys to the Melrose Ave. music spot to worship and learn at the feet of the masters: bluesmen including Lightnin' Hopkins, Mance Lipscomb, Sonny Terry & Brownie McGhee and Rev. Gary Davis, such mountain music mainstays as the Stanley Brothers, plains balladeers such as Ramblin' Jack Elliott, even Eastern European folk music revived under the direction of musicologist Mike Janusz.

"The Ash Grove," noted Alvin this night in a scorching electric blues song he wrote in tribute to the old club he and his brother Phil made regular pilgrimages to from nearby Downey, "that's where I come from."

If not for Ash Grove founder Ed Pearl, Alvin stressed, most of those blues greats would never have even come out to play in California. Folkie Arlo Guthrie, who as an unannounced guest opened the evening with a fine rendition of his dad Woody's anthem 'This Land Is Your Land,' said that his first West Coast trip was a 1965 gig at the club, when he was just a teen himself. Bob Dylan, Mick Jagger and fellow Rolling Stones mate Bill Wyman were among those who would stop by when they were in town, not as performers but as fans.

The music the youngsters heard in the late '50s and through the '60s, though, was the music of the displaced, the refugees, the kidnapped, those forced to leave their homes: Africans stolen into slavery, Jews fleeing poverty and pogroms, Irish escaping famine and oppression, English and Scottish crushed under the Industrial Revolution. The people playing the original Ash Grove were direct descendants of these immigrants, just a generation or two removed, if not immigrants themselves, caught between two worlds, not exactly as welcomed here as some myths would have it, but with no "home" to which they could even think of returning.

But for the wide-eyed kids, coming of age in a postwar, consumer-driven suburbia, arguably the most stable and comfortable situation in the history of the non-upper-classes, the yearning of the rootless somehow resonated. And it wove a thematic thread through this show, with Ramblin' Jack doing Woody Guthrie's satirical Dust Bowl migrant ballad 'Do Re Me' and Cooder singing Agnes Cunningham's comparable 'How Can You Keep On Moving (Unless You Migrate Too),' a song he learned at the Ash Grove.

Sure, it's pretty much a social anthropological cliche by now: the combo of Eisenhower-years blandness, the true establishment of a middle class and the mass-media explosion that opens up windows to other cultures and ideas sparks a new consciousness, music helps fuel awareness of civil-rights issues, a generation comes of age questioning the values of the power structure and, well, the '60s happened. Don't sell it short. The Ash Grove alone was perceived as enough of a threat to someone that it suffered three arson fires, the last closing it for good in 1973.

In the highlights of this concert, though, the tone turned personal more than political. Alvin's short set held a particularly deep note for the death a few days before of long-time musical saddle pal Chris Gaffney, with a line tossed into 'Ash Grove' and a dedication of a moving 'Shenandoah' to "my best friend." But then he couldn't wipe a big grin off his face as he and band accompanied elder statesman Ramblin' Jack through his digression-filled tales of the drifting life. Cooder, teaming with veterans Mike Seeger and Roland White for a tribute to "old timey" music, remembered nights during high school accosting Elliot and Carter Stanley as they came off stage to show him licks they'd played, and also imitating Pearl decrying any sense of commercialism even in performers mentioning albums they were promoting. Emcee Dr. Demento told of when he was simply young Barry Hansen working as a ticket taker, stage manager and everything else at the club. Unannounced surprised guest Ben Harper brought a real sense of currency and continuity by being joined by his mother, Southern California folk maven Ellen Chase, for an entrancing unplugged set with his band, including a sweet mother-son duet on Dylan's 'Tomorrow Is a Long Time.' (Word is Ben and Mom are going to make an album together, which, based on this little taste, will be a treasure.)

The inspiration took many forms: Holly Near, another graduate of the Ash Grove school, showed in her segment with East Coast duo Emma's Revolution how she channeled the lessons learned into a career of women's rights, civil rights and environmental activism. Culture Clash offered up political theater in the Ash Grove spirit with an excerpt from their 'Chavez Ravine,' another work about cultural and physical displacement in its pointed satire of the destruction of a multicultural community for the building of Dodger Stadium around the time the Ash Grove was founded. And younger musical artists Laura Love and Ashley Maher brought the Ash Grove aesthetic into newer contexts with, respectively, a distinctive brand of funk folk rooted in old spirituals and civil-rights anthems and a hybrid world music/dance bridging modern America and traditional Africa. And closing this first night, a motley Eastern European jam session blasted spiritedly into the wee hours.

The musical pinnacle came in the Cooder/Seeger/White set on a number in which Seeger played harmonica and fiddle simultaneously (a neat trick) on a mournful, haunting lick, singing lyrics about slaves being transported, with Cooder coming in for an electric slide solo that echoed Blind Willie Johnson's ghostly, despairing 'Dark Was the Night, Cold Was the Ground.' This performance at once captured that intersection of generations at the founding of the Ash Grove, that passing of rootless displacement into the realm of folklore roots, though the song itself shows that's nothing new. It was 'Stolen Souls From Africa,' a piece associated with white abolitionists more than a century before the Ash Grove even existed.

Pearl himself, in a brief address to the crowd, made a call for a new Ash Grove, something he said is needed in a time of complacency he likened to that of when he started the original club. The case can be made. Punk is by and large toothless, rap is becoming a caricature. There would seem not just a need but untapped demand for something really of substance, a unifying, galvanizing musical force that would bring in stray youth in search of, well, something. But is that even possible in the blogosphere era, when every music, every opinion, every thought is instantly accessible? No kid has to go to a club to learn about folk music or blues or anything today. Never mind creating something so threatening to the power structure that someone would burn it down once, let alone three times.