Sam Rivers, 88, an inexhaustibly creative saxophonist, flutist, bandleader, and composer who cut his own path through the jazz world, spearheading the 1970s loft scene in New York and later establishing an outpost in Florida, died Monday in Orlando, Fla. The cause was pneumonia, his daughter Monique Rivers Williams said.

With an approach to improvisation that was garrulous and uninhibited but firmly grounded in intellect and technique, Mr. Rivers was among the leading figures in the postwar jazz avant-garde. His sound on the tenor saxophone, his primary instrument, was distinctive: taut and throaty, slightly burred, dark-hued. He also had a recognizable voice on the soprano saxophone, flute, and piano, and as a composer and arranger.

His grandfather Marshall W. Taylor published one of the first hymnals for black congregations after emancipation, A Collection of Revival Hymns and Plantation Melodies, in 1882. His mother, the former Lillian Taylor, was a pianist and choir director, and his father, Samuel Rivers, was a gospel singer.

Mr. Rivers enrolled in the Boston Conservatory of Music in 1947 and later transferred to Boston University, where he majored in composition and briefly took up the viola and fell into the busy Boston jazz scene.

He made an important acquaintance in 1959: Tony Williams, a 13-year-old drummer who already sounded like an innovator. Together they delved into free improvisation, occasionally performing in museums alongside modernist and abstract paintings.

By 1964, Williams was working with the trumpeter Miles Davis and persuaded him to hire Mr. Rivers, who was with the bluesman T-Bone Walker at the time, for a summer tour.

Mr. Rivers' blustery playing with the Miles Davis Quintet, captured on the album Miles in Tokyo, suggested a provocative but imperfect fit. Wayne Shorter replaced him in the fall.

Mr. Rivers pushed further toward abstraction in the late '60s, moving to New York and working as a sideman with the uncompromising pianists Andrew Hill and Cecil Taylor. In 1970, he and his wife opened Studio Rivbea, a noncommercial performance space, in their loft on Bond Street in the East Village. It served as an avant-garde hub through the end of the decade, anchoring what would be known as the loft scene.

In 2006, the Vision Festival, a nonprofit New York event aesthetically indebted to the loft scene, honored Mr. Rivers with a Sam Rivers Day program. The names of two of the bustling pieces performed were, appropriately, "Flair" and "Spunk." - N.Y. Times News Service