Soloman Howard and Morris Robinson are sharing the role of Joe in "Show Boat,” but that’s just the start of what they have in common (Nikki Kahn/The Washington Post)

Here’s a gross misconception from some opera purists: Opera and the songbook need not fraternize. Musical theater, the lesser art, is a plaything for school kids who think Italian is a food, not the language of the best libretti.

It seems “Show Boat” is still crushing musical stereotypes, performed as both opera and musical since 1927. But the irony of Oscar Hammerstein and Jerome Kern’s masterpiece is that form mimicked their profound message: Who cares about labels? Just enjoy the show.

That message is center stage in the Washington National Opera’s production of “Show Boat,” running at the Kennedy Center through May 26. Indeed, the 100-plus cast members and a 50-piece orchestra show that opera and musicals can mix night after night, and that patrons and novices can enjoy the same art simultaneously, whether watching in the house or at Nationals Park during the “Opera in the Outfield” telecast on May 18.

But “Show Boat’s” larger message about labeling people according to race has implications in the opera world today. Two Washington natives performing in WNO’s “Show Boat” have experienced the challenges of working in an industry that often casts labels on voice type, age, race and appearance. Alyson Cambridge, whose father is Guayanese and mother is of Scandinavian descent, is playing Julie, a weighty role of a performer who conceals her race. Cambridge is sometimes considered too striking, too young, too soft, too something for the meatier roles she strives to play. But her interpretation of Julie proves that the soprano, who had her Metropolitan Opera debut at 25 in 2004, is no longer the sweet-sounding ingenue she was in her early 20s.

Soloman Howard, an African American bass in the WNO Domingo Cafritz Young Artist Program, is playing Joe in three shows, bringing him closer to his mentor Morris Robinson, who is also starring as the cerebral dockworker. Robinson is helping guide Howard through the pitfalls and nuances of one of the most popular solos ever written for the bass voice. “Ol’ Man River” is both blessing and bane, a memorable song that can pigeonhole a singer to the point that strangers in airports approach Robinson with a ‘I bet you could sing the heck out of ‘Ol’ Man River’” after hearing his low speaking voice.

Alyson Cambridge, soprano, plays Julie in the Washington National Opera's "Show Boat." (Nikki Kahn/The Washington Post)

For the seasoned soprano and rising star, “Show Boat” is an honor and a risk, a musical fraught with racial symbolism that can mirror the tensions within the opera world. But while Cambridge and Howard are aware of all the cultural and artistic freight, they refuse to let it limit their ambitions.

Alyson Cambridge

This isn’t the first time that soprano Alyson Cambridge, 32, has returned to her family’s home in Arlington while performing at the Kennedy Center. In 2010, she set up camp in her parent’s basement when singing the role of Clara in the WNO’s “Porgy and Bess.” Now, she’s reprising the role of Julie in “Show Boat,” which she played last year in the Lyric Opera of Chicago’s production, which WNO Artistic Director Francesca Zambello also directed.

Cambridge’s parents know her obsessive routine — the tea, the workout, not to interrupt her before a show — a regimen she began when she sang lead roles in musicals at Sidwell Friends School more than a decade ago.

Cambridge began singing opera at age 12 when she went for a lesson at the Levine School of Music in Washington. It was an afterthought in some ways, an extracurricular for a girl who excelled in academics and assumed she’d attend law school after college.

“My senior year, only my closest friends knew I left school once a week to take lessons at the Levine School of Music,” Cambridge said. “Singing in musicals was cool, but I didn’t show my stuff.”

Still, she applied to Oberlin College and Conservatory and double majored in music and sociology, the backup plan she’s never needed to employ. When she received a call from Curtis Institute of Music in Philadelphia during her senior year at Oberlin, she realized that opera would become her career. She would later leave Curtis early after winning a spot in the Metropolitan Opera’s Lindemann Young Artist Development Program, making her Met debut at 25. Still, after much success, playing Frasquita in “Carmen” or Mimi and Musetta in “La Boheme,” Cambridge admits that the career is demanding, one that requires constant growth and evolution to prove that she can take on new roles.

“I’m not the same singer that I was when I was 23,” Cambridge said. “My voice has continued to grow, it is louder and darker, so the repertoire is new. Unless you’re one of the lighter voice types that tends to pique around 25 or 26, it’s changing every three years, and you have to change with it.”

That can be difficult for a striking soprano like Cambridge, whose 25-inch waist and stunning features make her seem a natural for the catwalk, not for an opera house.

Cambridge admits that her looks sometimes get in the way; she fought hard for the role of Julie in “Show Boat,” proving that she could transform herself into an aged woman broken by alcohol and depression.

“Up until that point, I’d been playing mostly young ingenues, so I needed to pitch my voice lower, to show life weathering me,” Cambridge said. “I read the dialogue and sang for Francesca, and showed I could be a different woman in Act 1 and Act 2. Francesca said, ‘Okay. We buy it.’ ”

Cambridge also knows the risks of appearing in operas such as “Porgy and Bess” and “Show Boat” where race is a central theme. Because of her racial ambiguity, Cambridge has seen firsthand how race can become a factor in casting.

“I debated whether or not I should do productions of ‘Porgy and Bess,’ ” Cambridge said. “Word on the street was that once you start with ‘Porgy,’ you’re casting yourself as a black singer. But I’ve tried not to allow it to restrain me in my career.”

Cambridge is hopeful, though, that typecasting is becoming less common.

“Desdemona has been suggested to me quite recently, and it’s a role I’d love to play,” Cambridge said of Verdi’s “Otello,’ ” an opera in which race is a central theme, with Shakespeare’s Desdemona called the “white ewe.” “Some directors make race a focal point of the story line, while others look for the best voice. I don’t let it limit my aspirations in repertoire.”

Which is why Cambridge has chosen roles and pieces that speak to her talents, even those outside of the traditional canon. Along with “Show Boat,” she’ll star in Gershwin’s jazz opera “Blue Monday” at the Cotton Club in New York next month.

“I like singing arias, jazz and crossover, to mix lighter music with the intensity of heavier classical,” Cambridge said. “Audiences enjoy that diversity of programming. I’m not afraid to embrace it all.”

Soloman Howard

It could be said that Soloman Howard got his start the same way that his mentor did: on a football field. The 32-year-old bass, in his second year of the WNO’s Domingo Cafritz Young Artist Program, began singing at age 3 at Mission for Christ in Southeast Washington. The wide receiver, who played for Morgan State University while also singing in the chorus, learned about strength training, discipline and mental preparedness from the sport he’d leave for opera. Perhaps that’s why he and Morris Robinson get along so well — they both know how to perform on game day, a skill that’s essential for an opera singer.

Robinson, 44, the celebrated American bass who’s sharing the role of Joe in “Show Boat,” has much in common with the man he mentors. Once an All-American offensive guard at the Citadel, Robinson learned that the discipline and mental strength required for football could translate to operatic training — whether it’s practicing scales or brushing up on Italian or German.

“You approach football with a drive and discipline, and you have to approach opera in the same way,” Howard said. “You practice, study hard, and take care of yourself.”

Robinson refers to vocal training as “going to the gym,” and the phrase helps both of these basses make practice a priority.

The two met in 2006, when Robinson was performing with the Morgan State Choir.

“I heard this young guy walk up to me with a voice deeper than mine saying, ‘Hey, I just wanted to meet you,’ Robinson recalled. “I thought ‘Dude, you sound like my grandfather.’ ”

After the concert, Howard approached him and the two struck up a friendship, one built on shared repertoire and shared challenges.

“Seeing him out there doing, as another African American man that had some of the same interests, I thought, maybe if I follow the same path, I can end up where he is.”

Robinson says that mentorship is vital to the success of African American male opera singers, and both Howard and Robinson speak candidly about the isolation that African American males can face in the business.

“I can walk into an opera house with 100-piece orchestra, a conductor, stagehands and the whole crew, and I’ll be the only black person,” Robinson said.

Howard notes that young African American males are not often exposed to opera.

“Often in our community, we have to make excuses for why we’re singing opera,” Howard said. “But having an African American male that is the same voice type as me is very reassuring. To be able to reach out and get feedback, it’s motivating, and it removes the fear that I won’t be able to do it because of my race.”

Growing up, Howard was trained almost exclusively in gospel choirs. He joined Washington Performing Arts Society Children of the Gospel and later received solos in college. He started singing classical his freshman year of high school, after hearing some opera on the radio. The choral director heard him and entered him in his first competition in Canada, which he won without any classical training.

His entrance into the WNO was similarly serendipitous. He went to audition for the chorus after the application period for the Young Artist Program had closed. He stunned directors in his audition and a few months later, he sang for Placido Domingo and entered the Young Artists Program.

For “Show Boat,” Robinson has been guiding Howard through a singular challenge for the American bass, the singing of “Ol’ Man River,” the emotional ballad difficult for its musical heft and popularity. On top of popularity, most people have memories of Paul Robeson’s or William Warfield’s renditions, adding pressure to a newcomer like Howard.

“It’s tough to sing Joe,” Robinson said. “I was reluctant because I didn’t want to become known for singing ‘Ol’ Man River.’ There’s always a fear in our business of being typecast. But after learning more about the character . . . it isn’t a character that one should be ashamed to play.”

Robinson did worry about Howard taking the role of Joe so early in his career, in terms of typecasting and the importance of the character. While Robinson has an established opera career, having performed at houses around the country in shows including “Turandot,” “Don Giovanni” and “Il Trovatore,” Howard had his WNO debut last year in “Don Giovanni,” and is at the beginning of his career.

“I worried a little bit because it’s a large role, but he’s only doing three shows and doing the simulcast, so it’s good exposure and good to get used to the pressure,” Robinson said.

Howard believes that the role of Joe is helping him to prepare for his next role with the WNO; he’s playing Muhammad Ali in the WNO’s commission of “Approaching Ali.”

“Ali went through the same struggles [as Joe] and often used metaphors, so it does help in a way,” Howard said.

One might think that these two would be less friendly with each other. After all, the mentor could soon be competing with his mentee for parts in operas around the country. But they both agree that they’re not competing. Howard uses a sports metaphor to explain their friendship.

“Being athletes, I think of it as a relay race,” Howard said. “He’s passing the baton, and in the future, I’ll have to pass the baton. We never think of it as competition. We all run for the same team.”

Show Boat

The Washington National Opera production runs through May 26 at the Kennedy Center. 2700 F Street NW. 202-467-4600.