Cicely Tyson is an actress known for portraying black heroines. "The Corn Is Green" is Emlyn Williams' 1938 play about an English schoolmistress among Welsh coal miners.

In the production at the Kennedy Center's Opera House, Tyson plays the English schoolmistress. She's a disaster, but not solely for the reason you might suspect.

Taking an admittedly wild risk to play such an alien character, Tyson fails to project any character at all. As Miss Moffat she is a muddle: her stilted accent yielding to sounds from the West Indies; her heavy orator's gestures dissolving into sultry poses; her bright, humorless smile blinking on and off like neon.

"I don't understand you, I don't understand you at all," she tells her resistant proteg,e, a scruffy youth whom she has raised from the mines for a scholarship to Oxford. The lament comes out like a stemwinder delivered by Barbara Jordan.

Tyson is clearly working hard; it's certainly a chore to watch her in this three- hour exercise. There's no overriding reason why a black actress shouldn't play a white woman, even though it presents certain obvious problems. But Tyson takes thousands of stiff little steps in a role that demands a flying leap.

The performance seriously harms an otherwise skillful production, marring the Washington debut of the Elizabeth Theater Group, a company formed by Elizabeth Taylor and Zev Buffman. It's a shame that such tart comic performances as Marge Redmond's earthy Mrs. Watty, cutting through pomposity like a buzzsaw, and Mia Dillon's coquettish Bessie, glorying in becoming a fallen woman, aren't enough to save the show. THE CORN IS GREEN -- At the Opera House through August 14.