David Amram is a composer and a jazz musician and an author and a storyteller and a wanderer who, in the course of his 76 years, has befriended many a fascinating character. Charlie Parker, Dizzy Gillespie, Jack Kerouac and Woody Guthrie all fall into that category: All were quintessentially American figures who lived large, as Amram has done himself.

Fifty years ago, these men were part of a loose-knit community of artists in New York City; everyone knew everyone. Or soon would. And it happened, in 1956, that a friend of Parker's named Ahmed Bashir was crashing at Amram's $38-a-month apartment on the Lower East Side and awoke one morning to ask, "You want to meet Woody?"

"I said, 'Woody who?' " Amram recalls. "I really didn't know who he meant. 'Woody Herman?' "

"No, Woody Guthrie," Bashir answered.

This is how it started.

But before going further with the story, let's establish this: Half a century later, Amram is inspired by the "ineffable quality" he hears in the music of Guthrie, the Oklahoma-bred troubadour who befriended Leadbelly, inspired Bob Dylan, fathered folksinger Arlo Guthrie and died in 1967 of complications from Huntington's disease. He sees Guthrie as part of a "Whitman-esque tradition," one that "embraces the open road and all the people who live in this amazing vast country of ours." It's a tradition that "expresses the beauty part of life experience" in words and song.

And now Amram has taken Guthrie's most famous song, "This Land Is Your Land," and transformed it into an orchestral work titled "Symphonic Variations on a Song by Woody Guthrie." Commissioned by Woody Guthrie Publications - a family-run business, overseen by daughter Nora Guthrie - it will be given its world premiere performances by Symphony Silicon Valley this weekend at the California Theatre. Paul Polivnick conducts.

If you go, you won't just hear the familiar tune writ large for orchestra. You also won't hear, Amram says, a treacly pastiche of ersatz folk music.

For a time in the '60s, Amram was composer-in-residence for the New York Philharmonic, under Leonard Bernstein. His many works include two operas, a flute concerto composed for James Galway, even a "Triple Concerto" that has as "soloists" a woodwind quintet, a brass quintet and a jazz quintet. Symphony Silicon Valley performed it in 2005. Polivnick conducted that one, too, with exciting results.

Andrew Bales, the symphony's president, suggested doing another project, and Amram said, " 'You know, I've got this piece that I'm writing,' " Amram recalls, " 'and we don't have a definite premiere set,' and he said, 'Let's do it.' So it's just a terrific and fortuitous thing."

He has taken Guthrie's familiar musical theme and run it through a series of six transformations, re-harmonizing it, reorganizing it, at times outright hiding it amid his own musical inventions, which loosely follow the song's six stanzas - tracing Guthrie's journey along that famous "ribbon of highway," discovering this land and its people.

"My idea is to make it almost a biographical sketch," Amram says, speaking by phone from his home north of New York City, "showing Woody's travels and journeys" during the Depression, from the Dust Bowl to points west and east, eventually landing in New York. "So I took the six verses as a point of departure and used the song as a central theme and musically take the listeners on a kind of trip all over America, as Woody did, ending up in a big urban setting, New York City, which incorporates the music of many of the visiting cultures which have come to the United States. It's a way of showing that 'this land is your land.' "

Guthrie wrote his iconic song in 1940. (Its original title was "God Blessed America for Me," a retort to Irving Berlin's more jingoistic and similarly titled tune.) By the time Amram met Guthrie in 1956 - yes, we're back to the story - the troubadour was suffering from Huntington's disease: "His health was failing, but he was still so positive and full of energy," Amram says, "that it was hard to know that he had an illness and that he had such a hard life.

"Anyway, Ahmed Bashir and I had walked over to this little place in the Lower East Side, and there was Woody Guthrie - a very small, wiry man sitting at a kitchen table - and the amazing thing was he was wearing cowboy boots, and I'd never seen anyone in New York City wearing cowboy boots.

"And since I was brought up in a farming community of 200, a place called Feasterville, Pa., I could hear something familiar in his speech; the way he spoke and his accent reminded me of the farmers who used to get together at the neighborhood gas station where I grew up.

"And in this real Oklahoma drawl he was talking about all the things he was interested in knowing about. He talked about sports, about the Brooklyn Dodgers. And he talked about what it was like to go out to sea and how that gave him a chance to think about everything that happened on land, and sort it out. And he knew that I was a jazz player and a budding composer of music, and he talked about the different jazz players that he had heard and admired and about ballet and opera and classical music that he enjoyed.

"He was just one of those people who just had seemingly endless knowledge about so many different things."

Amram, though he may not say it, is cut from similar cloth. He grew up in farm country and had a storytelling uncle who was a seaman. At age 12, his family moved to Washington, D.C., to what was known at the time as a "checkerboard neighborhood" - black and white. There he heard, day and night, jazz, blues and rhythm and blues. He played piano, percussion and French horn - and had a French horn-playing girlfriend in Palo Alto. They had been high school sweethearts at a progressive boarding school in Vermont; after graduation, she returned to her family on the Peninsula, and he hitchhiked cross-country to visit her. This was in 1948; he also drove south that summer to perform in the Carmel Bach Festival orchestra.

Amram met Parker and Gillespie in the early '50s and was drafted into the Army during the Korean conflict. Moving to New York after his discharge, he studied at the Manhattan School of Music, played French horn in the band of bassist Charles Mingus, and became pals with folk singer Ramblin' Jack Elliott, Guthrie's protege.

After Guthrie's death, Amram would still run into Woody's second wife, Marjorie - who had danced with the Martha Graham Dance Company and gave classical music a prominent place in the Guthrie home - and the Guthrie children around New York. In the decades since, Amram has performed many times with Arlo Guthrie.

He is a collaborator, a fact well-known to Nora Guthrie, who has contracted with the Dropkick Murphys (punk), Billy Bragg (rock), the Klezmatics (klezmer) and other artists to set Woody's lyrics (there are plenty he never set to song) to music. And about two years ago, when she conceived the idea of giving "This Land Is Your Land" a new life in the world of classical music, she could think of only one composer who might find a way to do it: Amram. She gave him an assignment: Go to the annual Woody Guthrie Folk Music Festival in Okemah, Okla. He did; in fact, he has gone three summers in a row: "I just wanted to get a feeling of where he was from, what people talked like and looked like."

In Okemah, "a classic, pristine Western town," he met Guthrie's sister, Mary Jo, and some of the other old-timers who knew Guthrie. He jammed with local musicians and worked at absorbing the Oklahoma folk tradition, which owes a lot to American Indian and African-American chants and rhythms.

After initially feeling stymied by the commission - "How the heck am I going to do this?" - he began imagining himself into Guthrie's head. It's been said that the seed of the melody of "This Land Is Your Land" comes from an old hymn; Amram imagined Guthrie sitting in a church one Sunday morning, hearing the melody, and then carrying it around with him through his travels.

"And all around me a voice was sounding," Amram says, quoting a phrase from "This Land Is Your Land." That voice, to Amram, was "that melody; he couldn't get it out of his head. My raison d'etre is that, no matter where he went, whatever he did, he couldn't get that melody out of his mind. And in almost every variation of my piece, the melody sneaks in at some point. And as I moved along, each variation led me to the next one."

Amram's new composition begins with a "Theme and Fanfare for the Road," then takes to the road with variations that recall an Oklahoma Indian stomp dance, then, in sequence, Guthrie's seminal morning in church, a Texas barn dance, a "dream" of Mexico ("there's a wonderful tuba solo in the middle; the Mexicans use tuba in some of their polka music"), a "Dust Bowl Dirge" and then street sounds from New York: Caribbean, Jewish, jazz.

There's a Salvation Army band sequence, too. Maybe this imaginary band is collecting money for the unemployed men and women lined up outside the relief office in Guthrie's song: "In the shadow of the steeple," he sings, they wait and wonder "if this land's still made for you and me."

With all of this, Amram hopes to re-imagine Guthrie's travels and to underline Guthrie's affection for the American melting pot and for "the little things in life that are so precious." In a way, Amram says, "This Land Is Your Land," which has come to be sung around the world in many languages, carries the same message as Beethoven's "Ode to Joy," a message of universal brotherhood.

Amram says he isn't looking to do anything trendy or cutting-edge with his new piece. Leonard Bernstein once told him, "David, your job as a composer is not only to please yourself, but to contribute something to the repertory." He hopes the piece will have a shelf life and slowly wind its way into "the musical fabric."

He plans to attend this weekend's concerts in San Jose and already is plotting out his next compositions. He has a new autobiography going to press and can happily talk for hours about his recent performances - folk, jazz, classical - around the world.

"You keep on trying to improve," he says, "and that has a wonderful, medicinal effect of being anti-aging. When you have a real crowded schedule, there's no time to grow old. To put it in the vernacular, you just keep bopping til you drop."