True, the young lovers of “The Magic Flute” sometimes emerge from realistic stagings of Mozart’s last opera dripping and singed around the edges, but their trials are nonetheless symbolic. And, furthermore, they follow the traditional pattern of boy-meets-girl, boy-gets-girl with the two living happily ever after.

Kumudha and her Prince — they come from a 2000-year-old South India folk tale — invert the process; they start out blissfully together, but their happiness is soon shattered by their imperfect world.

There is good reason to draw parallels between the two operas, for Sellars asked Adams to compose a score for Vienna’s 2006 New Crowned Hope Festival. Sellars, curator of the program, sought new works from a cross-section of artistic genres sparked by “a conversation with the luminous music of Mozart’s final year.”

(New Crowned Hope was the name of the Masonic lodge to which Mozart belonged in Vienna.)

Adams immediately chose “Magic Flute” as his point of departure, stressing, however, that “the connection is more one of spirit than of substance,” yet pointing out that “both operas share a central theme of youth, the evolution of moral consciousness, transformation — both physical and spiritual — and magic.”

And like the “Flute,” “Tree” too is essentially a fairy tale, which the Storyteller begins: “Children, I want to tell you a story.”

It is a story excitingly told through the intense interaction of text, music and dance that makes it a unique achievement of music theater.

Music theater?

Yes, for the collective concept avoids the question of whether “Tree” is actually an opera. Scholars will argue the point, stressing — after all — that the three San Francisco performances of the work were given by the Symphony in Davies Hall, not across the street in the War Memorial Opera House.

And, indeed, ‘Tree’ has something of an oratorio about it, with the Storyteller functioning much as does the Evangelist in the Passions of J. S. Bach.

But why worry about the label for a work so endlessly moving?

“Tree” calls for only three singers — Kumudha, the Prince and the Storyteller, who are seconded by a trio of dancers, Doppelgänger, as it were, who bring animation to the narrative and amplify the inner emotions of the singers.

Vocalists in San Francisco — as in Vienna and Berlin — were soprano Jessica Rivera, stellar as Nuria in Osvaldo Golojov’s “Ainadamar” at the Santa Fe Opera in 2005, tenor Russell Thomas and bass Eric Owens. All three are young artists of promise, distinguished by their thorough command of this score and their obvious commitment to it.

The Javanese dancers — Rusini Sidi, Eka Supriyanto and Astri Kusuma Wardani — were also responsible for the choreography for this semi-staged production.

Action was confined to three overlapping ovals that shared the Davies stage with the orchestra and to a smaller space above and to the left of the ensemble. The simplicity of the staging complemented the leanness of Adams’ score and of the libretto. Written by Sellars and the composer, the text runs a mere 9 pages in the SFS program book.

The overwhelming quality of the work is its beauty, a word that one uses with hesitation in talking about new music. Too often suggests the warmed-up Brahms of the now largely forgotten New Romanticism of a few decades ago or the embarrassed hovering at the edge of dissonance where many modernists dwell, fearful of losing their audience should they move one step further from the triad.

Adams’ embrace of tonality is unashamed and without apology, for it comes from the heart; this — like its story — is music with a soul.

And, yes, Adams’ early minimalism (he turned 60 in February) is still present, but only as a subtext in a score, in which craftsmanship and accessibility are remarkably balanced.

For “Tree” too, one might say, marks a transformation in the career of this, America’s most-performed living composer. Here it is the lyricism of long sustained lines that dominates; rhythmic figures, although subtle, are never complex.

The work is through-composed — without big arias or “numbers” — and this accounts for its easy and seamless flow.

“Tree,” which runs 2.5 hours with a single intermission, is clearly a major work. It centers on four scenes of transformation, for — recalling Richard Strauss’ Daphne — Kumuhda is able to change herself into a tree, which she does to escape the recurrent miseries of her life.

For these scenes, the backbone of ‘Tree,” Adams has written music that is truly transcendent — rich in its sonorities and textures and mesmerizing in communicating the emotional impact of the story.

Like the “Sea Interludes” in Britten’s “Peter Grimes,” these sections of the score will no doubt become an orchestral suite.

Essential to the work is the chorus, which Adams says should number at least 40 singers. The SFS gave him more than twice that number, superbly rehearsed by David J. Xiques, the brightly dressed ensemble was a major participant in the drama at hand.

“Tree” is scored for a symphonic ensemble of medium size with a massive percussion battery.

At a pre-performance interview Sellars characterized the work as a masterpiece of “joyful transformation,” which sums up its essence and its impact.

Kumuhda and her Prince find each other and their love again at, but only after a journey through pain and adversity, and it is this honesty about life and the blows that it deals that account for the authenticity of “Tree.”

Like the last two of Mozart’s 40 symphonies — the pensive D Minor and the exuberant “:Jupiter” — this is the other side of the coin explored by Adams and Sellars in their 2005 “Doctor Atomic,” the tale of physicist Robert J. Oppenheimer’s Faustian flirtation with the force of infinite destruction.

Indeed, Sellar’s recently referred to the earlier opera as ‘Adams’ ‘Götterdämmerung.”

“A Flowering Tree” is a co-commission of the San Francisco Symphony, Vienna’s New Crowned Hope Festival, the Berlin Philharmonic, London’s Barbicon Centre and the Lincoln Center for the Performing Arts in New York. The composer conducted the Viennese premiere; Simon Rattle was on the podium for the Berlin performance.

And, by the way, “Doctor Atomic” will be on stage at Chicago Lyric Opera between December 14, 2007 and January 19, 2008.

Wes Blomster