There are few musicians in jazz -- or anywhere else for that matter -- more productive, curious and creative than pianist and composer Fred Hersch. In recent years, his studio output has included a collection of audacious solo improvisations, a highly personalized "songbook" series saluting Thelonious Monk, Billy Strayhorn and Rodgers and Hammerstein, and several thoroughly modern jazz collaborations featuring such artists as trumpeter Dave Douglas and guitarist Bill Frisell.

Now comes the mid-size ensemble piece "Leaves of Grass," an eloquently orchestrated celebration of Walt Whitman's poetry, vision and, above all else, humanity. Presented at Lisner Auditorium on Saturday night, the concert found Hersch and a nine-member group turning a Whitman's sampler into a fairly seamless and frequently inspired evening of chamberlike jazz.

Hersch, who composed all the music, was self-effacing onstage. He soloed sparingly, in a typically thoughtful and harmonically inventive manner, and appeared intent on making certain that his contributions quietly served the subject matter. Yet he's created a suite inspired by Whitman's sweeping reach, one that blends melodic contemplations and elements of swing, blues, Latin music and the occasional harmonic clash with the rich sonorities of Erik Friedlander's cello and a horn section capable of embracing both jazz and classical idioms. As the concert unfolded, slides of commissioned artwork by San Francisco painter Marianne Kolb were shown on a projection screen behind the ensemble, adding an intriguing dimension to the performance.

The most challenging roles were assigned to jazz vocalists Norma Winstone and Kurt Elling. Each managed to bring Whitman's passionate word craft and towering spirit into sharp focus, steering clear of glib jazz phrasing or meandering passages of scat. Elling, who is well versed in the jerky cadences of beat poetry, abandoned stylistic quirks in favor of a more articulate, measured and lyrical approach. As a result, even fiendishly worded sections of "Song of Myself" (to wit: "stuffed with the stuff that is coarse and stuff'd with the stuff that is fine") were rendered comprehensible and tuneful. Of course it didn't hurt that Elling's baritone has seldom sounded more warm and resonant.

Winstone's voice, a lovely, wistful, wide-ranging soprano, twined with brass and reeds to create a haunting aura, and cast a quiet spell of its own beginning with "Song of the Universal." The British vocalist also contributed an original lyric titled "At the Close of the Day," a ballad that tenderly complemented Whitman's whirling rhapsodies and romantic musings.

Hersch chose the Whitman texts, and he didn't waste the opportunity to vibrantly orchestrate verse teeming with imagery and noise ("The ring of alarm-bells, the cry of fire, the whirr of swift-streaking engines and horse carts with premonitory tinkles and color'd lights"). In addition to cellist Friedlander, the ensemble performances were consistently enhanced by trumpeter Ralph Alessi, trombonist Mike Christianson, bassist Drew Gress and reedmen Michael Moore and Tony Malaby. No one, though, was more responsible for shading the moods than drummer-percussionist John Hollenbeck, who used brushes and sticks to marvelous effect.

At evening's end, the audience, which occupied only a quarter of the seats in the venue, sounded twice its size when it rewarded Hersch and his colleagues with a long standing ovation -- a response richly deserved.

Pianist Fred Hersch was sparing in his solos, generous in sharing the stage in his "Leaves of Grass."