Grandma Moses may have been one of the most beloved Americans of the 20th century, but you've got a serious problem on your hands if you want to put her life on the stage. She was a very late bloomer.

Not until she was into her seventies did Anna Mary Robertson Moses take up the brushes and paints that eventually brought her worldwide renown. Up to then she was a farm wife who worked hard, gave birth to 10 children (and lost five) and prided herself on her fruit preserves.

If we are to believe "Grandma Moses: An American Primitive," the documentary in theatrical clothing that opened Wednesday night at Ford's Theatre, she also admired the yellow of the mustard grass in the Shenandoah foothills, the purple of the cherries at the top of the tree and the "true red" of a pair of long johns flapping on the clothesline. So, I venture, have many others. In the first act of Stephen Pouliot's play, the dear lady is 45, altogether upstanding and altogether unexceptional.

The self-taught artist who painted bucolic scenes on Masonite board (that way you could wash them with soap and water if they got dirty) doesn't put in an appearance until the second act. By then she's 100 and, as Cloris Leachman plays her, everything the legend claims: firm, feisty, spry enough to manage by herself, thank you very much, and supremely unaffected by the fuss the world wants to make over her.

The audience applauds the transformation. And why not? This is old age as we would all like it to be -- serene, respected, productive. But we're really no closer to drama than we were an act earlier. The late bloomer has bloomed, that's all. There really isn't a great deal more to it than that.

Grandma Moses seems to have gone about painting as she went about life -- with as little stuff and nonsense as possible. She had no theories of art. First she found a frame she liked, then she made a picture to fill it. Asked in the second act how she paints, she replies crisply, "From the top down." Informed there might be some interest in her version of "The Last Supper," she brushes the offer aside with equal crispness. "I will not," she says, "paint something I did not attend."

Instead, she drew her inspiration from the hills around her home in Eagle Ridge, N.Y., and from the remembered landscapes of her childhood. A generous selection of her work is flashed on an upstage scrim to sprightly musical accompaniment, and it contributes to the warm feelings the show fosters in the auditorium. Hers was a well-ordered world in which everything and everyone had a place.

Drama is not made of such tidiness, however. From the evidence at Ford's, whatever stirred the soul of Grandma Moses she kept to herself, as any good Yankee would. "If I didn't start painting, I would have raised chickens," she explains, the matter-of-fact tone implying that one activity is as valid as another. What's important is keeping busy.

Pouliot has populated the proceedings with seven other characters -- Grandma's husband, her father, her brother, a couple of mailmen and, most significantly, Otto Kallir, the Austrian-born art dealer who championed the artist and guided her career as much as she let it be guided. They are all played by the same actor, Peter Thoemke, who employs a variety of hats, wigs and accents, which do not entirely hide his lack of versatility.

Having a second actor on the premises, however, produces little in the way of scenes. The two acts of "Grandma Moses" function primarily as before-and-after pictures. The first act allows Leachman to display a vigor of step and a quickness of eye, as she packs up the farm in the Shenandoahs and prepares to move north.

Of course, we are being set up for the transformation, a slowdown, really. But it is duly impressive when it comes. Leachman's voice crackles like an old radio. The eyes squint and the head bobs in an attempt to bring the world into focus. The feet are unsteady and the hands have a tendency to open and shut by themselves. The mind, however, remains proud and resolute. Leachman doesn't have a lot of revealing words to work with, but in her assertion of mind over aging matter, she imparts dignity and courage to Grandma Moses.

Well, she was something of a wonder and you can't disparage the show for wanting to evoke her qualities -- the self-reliance and modesty we like to think are quintessentially American. At Ford's, nobody waves a flag. But "Grandma Moses: An American Primitive" indulges in a related activity. It parades a set of values across the stage and asks the members of the audience to stand.

Opening night, they did.

Grandma Moses: An American Primitive, by Stephen Pouliot. Directed by Howard Dallin. With Cloris Leachman and Peter Thoemke. At Ford's Theatre through July 8.