The first thing the audience hears at the beginning ofEisa Davis'play “Bulrusher” is the title character, a mixed-race teenage girl in Northern California in 1955, declaiming a poem about her own beginnings.

”I float in a basket toward the Pacific, hands blue as huckleberries,” she intones. A few lines later, she explains. “The woman who bore me wrapped me, gave me to the green of the Navarro, named me silence.”

It’s a distinctive opening, aptly steeped in the evocative mysteries that surround the girl’s past. Bulrusher is found as an infant, floating in the river like Moses in the Old Testament, and she grows up in Boonville, at once a member of the small, tight-knit community and a permanent outsider. Her apparent gift of clairvoyance doesn’t help her to fit in.

But the poem is also an apt reflection of the origins of the play itself, which opens Wednesday, Nov. 1, at Berkeley Repertory Theater, and then reappears Aug. 3 in a new operatic guise at West Edge Opera.

In its earliest incarnation, Davis said in a telephone interview from her home in Brooklyn, “Bulrusher” consisted of a series of poems.

“这是二十多年前,”她回忆道。”I’d been writing a lot of poems and thinking in a lot of poetic ways. But I was also working as a musician in a duo with a composer named Daniel P. Denver, and one day he told me he wanted to write a song cycle.”

So Davis put together eight poetic texts, inspired by her love of the language and landscape of Mendocino County. But it wasn’t enough.

”The entire plot of the play showed up in no time,” she said, “and it just made me hungry for a full piece that fleshed out that story. So I just started writing.”

”Bulrusher” wound up being a wondrous amalgam of song and story, mixing personal drama, myth and historical references. There are extended stretches of dialogue making use of Boontling, the quirky insider dialect of the Anderson Valley that dates back to the late 19th century.

But the choice of 1955 as a chronological setting was far from arbitrary, Davis said. That was the year of the Montgomery bus boycott and the murder of Emmett Till, both of which become relevant when a girl from Alabama arrives in Boonville with a new perspective on race.

”One of the things I wanted to explore in the play was the difference between the experience of anti-Black racism in the Southeast and in California,” Davis said. “Everyone thinks these are two Black girls, and that culture is monolithic. But of course it’s not. So I wanted to reveal that discrepancy.”

”Bulrusher” premiered in New York in 2006 and had a rough early history, including a lukewarm review in the New York Times whose memory still stings. But after it was named a finalist for the Pulitzer Prize, the play took wing, including anadmired productionat Berkeley’s Shotgun Players a year later.

Now, in addition to the Berkeley staging directed by Nicole A. Watson, “Bulrusher” is undergoing yet another metamorphosis.

Davis and San Francisco composerNathaniel Stookeyare turning it into an opera. Oakland’s West Edge Opera gave apreviewof a couple of scenes from it in 2021, and have planned a world premiere production for August.

It might seem like a bold undertaking to create a new musical layer for a stage work that is already so deeply infused with music from its inception. But Stookey, whose previous opera was the superb one-act work “Ivonne,” is undaunted.

”There are two things that appealed to me about setting 'Bulrusher' to music,” he said in a phone interview. “One is that I’m very interested in the musicality of language, not just in the poetic sections but all through.

”The other is that the characters are uncommonly three-dimensional and appealing in their complexity. They’re both flawed and sympathetic, and conveying that is much more interesting than just conveying a straightforward villain.”

Davis and Stookey first worked together in 2008, when she was one of two vocal soloists in his orchestral song cycle “Zipperz,” which had its premiere at the Oakland Symphony under the baton of thelate conductor Michael Morgan. The two Bay Area natives discovered a shared love for both music and theater.

Davis, the niece of activist and author Angela Davis, enjoys a career that includes writing, music and acting. She has performed as a singer-songwriter, and has acted in film and television, including roles in “The Wire,” “House of Cards” and “Succession.”

She said she welcomed the prospect of working with Stookey to recreate “Bulrusher” in another medium. At first, she says, they expected that the composer could adapt the libretto himself.

”But once we had a reading of the proposed libretto, I realized that I would have to be wholly involved with the process. There’s so much that I had to be able to share with him about the language and the characters.”

The process was made easier, Stookey said, by Davis' musical expertise.

”One of the benefits of working with Eisa is that she is someone who has set words to music herself, so she understands that my needs are different from those of the play.

”People can talk about all manner of things in a play, but in an opera that would take an extra hour. So I need fewer words. And she gets that. The notion of cutting is not immediately terrifying to her.”

In its theatrical form, “Bulrusher” takes the full measure of its story, with plot turns, narrative digressions and scenes from midcentury rural life in Mendocino County. But at heart, the piece retains its original genetic code, in a few lyrical and highly compacted poetic interludes.

The opera represents a new twist in the river-like journey of the piece and its protagonist. As Bulrusher herself says at the end of that first poem, “I am born into a new language.”

Reach Joshua Kosman:jkosman@sfchronicle.com