Lady of the Manner

Lady Croom, the 18th century mistress of a beautiful country estate and the mother of a brilliant 13-year-old girl, sweeps onto the stage at South Coast Repertory with the panache of a grande dame.

Her charming manner, not to mention her vivacious beauty, invites all the guests at Sidley Park, no matter how foolish or obtuse, to bask in her warmth--thanks to Marnie Mosiman’s unusual interpretation.

The role, which helps anchor Tom Stoppard’s large-cast “Arcadia,” also sets the tone of SCR’s Mainstage production in a significant way. By making the formidable Lady Croom more personable and appealing than she is often played, the drama itself, brimming with intellectual discourse, is made less distant.

“I relate very much to having a daughter,” said Mosiman, who has two sons. “That may not be a very strong part of other people’s ideas of Lady Croom. She probably looks like a rather glib and unfeeling mother. But I don’t think that’s necessary.

“I also relate to the fact that she’s brighter than her surroundings,” Mosiman added in a recent interview at the Costa Mesa theater. “There are a lot of times when she says something and doesn’t let the others know she thinks they’re really stupid or just not getting it.”

Lady Croom isn’t the first SCR role shaped by Mosiman’s considerable talent. Last season she played Ouisa, the pivotal character in John Guare’s “Six Degrees of Separation.” Times reviewer Don Shirley wrote that Mosiman “captures Ouisa’s sense of stylish fun at the beginning . . . and her shaken sense of self at the end.”

Before that, she appeared at SCR in “Hay Fever,” “Loose Ends,” “Ashes,” “Becoming Memories,” “Benefactors” and, in a dazzling performance as Ann and Dona Ana in “Man and Superman,” displayed her versatility as both a comic actor and an operatic soprano.

Mosiman grew up near Minneapolis and majored in music composition at college. “I played piano and guitar. I sort of put myself through college that way, and I did a lot of theater.”

The ebullient, auburn-haired performer started out as a classical singer. “But I didn’t appreciate opera at the time,” she said, “partly out of my own ignorance and partly because the productions I saw were just too silly to accept.”

Unable to connect with opera but also not a “belty pop singer,” Mosiman sought work as a dramatic actor. She got her first paying job in the theater as a dancer, however, and landed her first role in New York in the national touring company of the off-Broadway musical “Godspell.”

“In those days,” she said, “you were either a singer/musical-comedy person or a serious actor. I had this ‘Godspell’ thing on my resume. So that’s what everybody looked at. I thought if I don’t leave New York and go do regional theater, I’m sunk.”

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Today, Mosiman does both drama and classical music, sometimes appearing with her husband, John de Lancie (of “Star Trek” fame), who often works with major orchestras in pieces that require narration.

Last summer, for example, she played the Witch of Endor in Arthur Honegger’s oratorio “Le Roi David,” with Charles Dutoit conducting the Philadelphia Orchestra, and St. Joan in Honegger’s “Jean D’Arc au Bucher” at the Aspen Music Festival, with David Zinman conducting the festival orchestra.

“St. Joan was fabulously exciting, one of the most thrilling things I’ve ever done,” said Mosiman, who also sings in the chorus of the Los Angeles Master Chorale.

“Jean D’Arc au Bucher” had 370 performers--a full orchestra, a 160-voice choir, a children’s choir, 18 soloists and “me,” she said, “in the middle of the platform tied to a stake the whole time. I can’t tell you how exciting it felt.”

More exciting than playing Lady Croom?

“Different,” she said. “It’s hard to get to the intensity of such an emotional experience without the music and the voices going all at once.

“I think ‘Arcadia’ is electrifying theater. What pleases me is that I’m playing a role with many levels--the mother, the lover, the host--which is what I actually love doing in real life.”

* “Arcadia” continues through Sunday at South Coast Repertory, 655 Town Center Drive, Costa Mesa. (714) 708-5555.