“Hair” is coming to Marin County’s Mountain Play, but actor Jeff Wiesen has a big caveat for aging Bay Area hippies: Don’t expect to see the musical’s famous nude scene. This production of “Hair” has been cut.

“If you’ve ever been to the Mountain Play, you know there are thousands of kids,” says Wiesen. “It’s family time in the middle of the day. Maybe in 1969 it would have been OK for kids to see naked people. Today it’s not.”

Then, he adds with a laugh, “I was so upset.”

With his tie-dyed shirts and long beautiful hair, Wiesen could easily pass for a clothing-optional hippie circa 1967. But at 26, Weisen is a generation or two removed from the counterculture depicted in “Hair.”

He grew up in San Rafael attending Congregation Rodef Sholom, where he was bar mitzvahed. So to play the lead role of Berger, the trippy wild man who sings the title track, Wiesen had to research the social climate that gave rise to “Hair.”

“It was such a groundbreaking show when it came out,” says Wiesen. “It was so important culturally and politically, and it’s very poignant right now. In conversations with the case we talk about war and imperialism, topics very much mirrored today.”

Even though he was born years after the show premiered, Wiesen knows “Hair” well. He appeared in a previous production 10 years ago when he was still a high school student. What does he remember best about that experience?

“It was exhausting,” he says. “It’s an incredibly frenetic play, a lot of fun, but I remember dripping sweat and vowing never to do it again. I don’t think I understood it back then. I didn’t have much of a historical perspective of the hippie movement. I do now.”

The musical did break theatrical ground when it premiered in 1967. “Hair” follows a band of merry pranksters called the Tribe through their New York adventures during the Vietnam War era. Sex, drugs and rock ‘n’ roll figure prominently, as does plenty of music. The show’s best-known songs include “Age of Aquarius,” “The Flesh Failures (Let the Sunshine In),” “Good Morning, Starshine” and the title song.

The Mountain Play version, coming 40 years after the original Summer of Love, includes those and plenty more. And some clever production designers did their hippie research, as the production opens with a real VW bus, complete with flower decals, driving right on stage. The doors open and clouds of smoke pour out, along with a few toasted members of the Tribe.

“Berger is this crazy freewheeling egotistical hippie,” says Wiesen. “He likes to do drugs, get tactile with the ladies, dance. He is impulse oriented. All actors are a little like Berger, so in that way, it’s a release for me. I’m not quite that way, but that’s the beauty of acting.”

Though “Hair” is by no stretch of the imagination a Jewish musical, Wiesen says show has already had an impact on his Jewish life.

“During the rehearsal process, I found my way to Birthright,” says Wiesen, referring to the program that provides free trips to Israel for Jews age 26 and under. “This is the last year I’m eligible, and I’m committed to a trip in June. I don’t think it’s a coincidence. The show is very spiritual, so getting in touch with that helped me find Birthright.”

After Israel, Wiesen will return to Los Angeles, where he’s been living since graduating from UCLA’s theater department. His mother was a pianist, exposing him to musical theater at an early age. In recent years, Weisen has been a regular performer at Malibu’s famed Theatricum Botanicum, as well as landing a few TV and film roles.

However, he won’t cut his hair any time soon. Gambling he might make the cast, Wiesen started growing it a year ago when he first heard the Mountain Play would be staging the musical. But after the final curtain falls, he moves on to a production of “Dracula,” which also calls for long hair.

“I was going to buzz-cut it,” he says, “but now … ”

“Hair” plays 1 p.m. Sundays, May 20-June 17, and Saturday, June 9, at the Mountain Play, Cushing Memorial Amphitheatre, Mt. Tamalpais State Park, Mill Valley. Tickets: $28-$32.50. Information: (415) 383-1100 or online at www.mountainplay.org.