Joseph Byrd, an avant-garde musician and composer who emerged from the anti-art Fluxus movement to rattle the flower-power sound of the 1960s with the critically acclaimed, if challenging, experimental psychedelic band the United States of America, died on Nov. 2 in Medford, Ore. He was 87.

His death was announced in a paid death notice published in The Los Angeles Times.

The United States of America formed in Los Angeles during the peak of psychedelia, but, commercially speaking, the group never came close to acid-rock kingpins like Jefferson Airplane, or even lesser known groups like the Electric Prunes.

Lasting barely two years, the band both intrigued and flummoxed listeners with its early experiments in electronic music, dreamy ruminations on Che Guevara and jarring cross-genre forays that drew from influences as diverse as Country Joe and the Fish, Jelly Roll Morton, 19th-century marches and antebellum minstrel show numbers.

Its 1968 debut album, titled simply “The United States of America,” peaked at No. 181 on the Billboard 200 — and turned out to be the group’s last.

Still, that one album garnered no shortage of critical plaudits over the years. Writing on the website Allmusic, Jason Ankeny called the United States of America “among the most revolutionary bands of the late ’60s.”

In 2004, Cameron Macdonald wrote on Pitchfork that while the band was “never immortalized by Pepsi commercials or Time-Life 20-disc retrospectives,” its album “still stands above the work of most of their Monterey-era, psych-rock peers.”

Rolling Stone listed the album as No. 28 on its 2021 survey of the “40 Greatest One-Album Wonders.” “In the ’60s,” the magazine observed, “a few brave punks were not afraid to make some noise with the squawking, blipping textures of embryonic electronics,” adding that “they made California’s acid-rock present drip into the acid house future.”

The group has long been cited as a forerunner of Krautrock, the experimental electronic sound of German bands like Kraftwerk and Tangerine Dream.

In an era when seemingly every young person with a guitar and a fringe jacket headed to the family garage with dreams of starting the next Doors or Grateful Dead, Mr. Byrd stood far apart.

A former ethnomusicology instructor at the University of California, Los Angeles, he was an authority on Civil War-era and other early American music, and a former student of John Cage, the experimental music titan and a godfather of Fluxus, which emerged in New York City in the early 1960s.

The aims of that eccentric movement, which included Yoko Ono and Joseph Beuys, might best be summarized by Alison Knowles’s “Make a Salad,” a 1962 work of performance art that consisted of her doing just that to a musical accompaniment before serving the audience the fruits — or vegetables — of her labor.

After honing his craft in performance “happenings” in downtown Manhattan lofts, Mr. Byrd returned to Los Angeles. With Marxist leanings and a fierce opposition to the Vietnam War, he saw rock music as “a logical step to seek a bigger audience, to turn art in a more socially radical direction,” he said in a 2013 interview with It’s Psychedelic Baby Magazine.

There, he created the United States of America in 1967 with the folk vocalist Dorothy Moskowitz, a former romantic and artistic partner, and the composer Michael Agnello, an anarchist. Mr. Agnello later quit the band after it signed with Columbia Records — in Mr. Agnello’s view, a sellout to the corporate masters.

Yet the spirit of rebellion lingered. “Using the full name of the country for something so common as a rock group,” Ms. Moskowitz once explained, “was a way of expressing disdain for governmental policy. It was like hanging the flag upside down.”

While revolution was in the air in the rock world by 1968 — look no further than the Beatles’ “Revolution” — Mr. Byrd did not consider his band to be followers.

“There was no ‘school’ in which we considered ourselves,” he said in an interview with the culture site Clouds and Clocks in 2004. Rather, he added, “I regarded the avant-garde art community as my peer group.”

Mr. Byrd was born on Dec. 19, 1937, in Louisville, Ky. During World War II, the family moved to Tucson, Ariz., and his father purchased a mine near the Mexican border in a failed attempt to sell ore to the government.

Young Joseph’s prime influences were jazz artists like Duke Ellington and Stan Kenton, although his band as a teenager, the Debonaires, which featured him on accordion and vibraphone, played “the awful pop music that was on the radio,” he recalled.

After high school, he enrolled at the University of Arizona, where he played in a jazz combo and studied under the composer Barney Childs. After receiving a bachelor’s degree in music, Mr. Byrd earned a teaching assistant post at Stanford University, where he received a master’s degree before heading to New York in 1960 to study under Mr. Cage.

In the Fluxus scene, Mr. Byrd became known for his complex musical collages. His first concert, held at Ms. Ono’s Chambers Street loft, featured the pianist and composer David Tudor and included a piece in which accompanying players created wispy sounds by slowly releasing air from inflated balloons.

“In New York, we were all subsumed into a protean energy,” he told It’s Psychedelic Baby, “less a school of composition than an attitude: We were redefining art itself.”

In 1963, he accepted a teaching post at U.C.L.A. and eventually created a music workshop with the jazz trumpeter Don Ellis before abandoning academia a few years later to focus on rock.

Inspired in part by the anything-goes spirit of the Beatles’ “Sgt. Pepper’s Lonely Hearts Club Band,” the United States of America announced its arrival with “American Metaphysical Circus,” the first track off its album. The song layered circus-ready calliope lines over Sousa-esque marching band stylings before drifting into vaguely astral rock that suggested the early Syd Barrett-era of Pink Floyd, albeit with a female singer.

The band’s live shows included various freak-out trappings of the era, including a large neon American flag and a full-size plaster nun. “We may have been the first to use fog machines,” Mr. Byrd said.

“We were plunging into rock without any real knowledge of, or experience in, the medium,” he told It’s Psychedelic Baby. “We had played Cage and Stockhausen, African and Indian music, and I thought we could simply bring all that to rock. But we knew almost nothing about the roots of rock ’n’ roll.”

Strained by internal divisions, the group soon disbanded. Mr. Byrd returned in 1969 with an album titled “The American Metaphysical Circus,” credited to Joe Byrd & the Field Hippies. It went nowhere.

Over the years, he collaborated with noted musicians like Phil Ochs, Ry Cooder, Linda Ronstadt and David Lindley. He also wrote music for numerous television and film projects, including Agnès Varda’s “Lions Love” (1969).

Mr. Byrd went back to academia, teaching at California State University, Fullerton, into the 1980s and later at the College of the Redwoods in Eureka, Calif.

His wife, Barbara Bennett, who was known as Beni, died before him, according to the published death notice. It said he is survived by a daughter, Clarissa Byrd; a brother, Ruddell; and two grandsons.

While his band never notched a hit, Mr. Byrd took pride in its legacy, particularly its collage approach to recording.

“I don’t find so much collage in American music,” he told Clouds and Clocks, “but it does seem to have taken hold in the British bands,” including Portishead, Broadcast and Radiohead. “If that’s my influence, I’m delighted.”