Lanie Robertson’s “Alfred Stieglitz Loves O’Keeffe,” running through July 11 at Acadia Repertory Theatre in Somesville, is a biomemory drama about two of the 20th century’s most documented artists. Photographer, editor and gallery owner Alfred Stieglitz (1864-1946) changed the direction of American art with his bold exhibitions and tireless support for favored artists and their work. Matisse, Cezanne, Braque and Rodin all were shown in his gallery. Paul Strand, John Marin, Marsden Hartley and Arthur Dove benefited from his enlightened eye. Unquestionably, his second wife, Georgia O’Keeffe (1887-1986), the celebrated painter of sensual flowers, was the chief beneficiary of his genius, generosity and gumption.

Robertson, who has made a career out of writing historical dramas (about Billie Holiday, Joe Orton and others), knows that real life provides some of the best dramatic characters. But even figures as compelling as Stieglitz and O’Keeffe need more than a two-hour encyclopedic piece to be interesting as a play.

Director Wayne Loui has done his best to keep Ken Stack and Jenny O’Sullivan on course through a script that is more presentational than emotional and evocative. The action flows boisterously primarily because there’s a lot of energy between the two. But any success is a clear case of actors enhancing an episodic script, which begins at Stieglitz’s funeral, flashes back through a 30-year period and includes spotlighted asides.

But even these practiced performers can’t entirely save the night. For all Stack’s elasticity in performance – who will ever forget his portrayal of Roy Cohn in Penobscot Theatre’s 1999 production of “Angels in America”? – he never quite becomes Stieglitz. Oddly, it seems to have little to do with his style, which is lively and fun. But Stieglitz’s real image neither faded nor entirely appeared on opening night.

O’Sullivan, in some ways, has the opposite problem. Though prettier than O’Keeffe, she adopts the scarf and black garb that marks her undeniably as the artist. Yet her role is so narrowly written that it leaves her little else to do but whine, rage and pout. O’Keeffe’s own brooding image is perhaps one of most recognizable in American photography – largely because Stieglitz took more than 300 photos of her. (The late George Daniell, who lived in Trenton, also took famous shots of her.) And it would be easy to back her into that somber corner.

But O’Keeffe was actually quite humorous – even if she was bitter over the treatment of women artists in a male-dominated field. In Robertson’s play, the wit is absent. If Stieglitz loved the O’Keeffe of this play, one can’t help wondering: Why? She’s intolerably bratty, and O’Sullivan has little choice but to go with it.

The third actor never makes an appearance in the play but his presence is felt strongly in the flashbacks and references to his own art. Marsden Hartley, the Maine painter who did indeed infringe on the Stieglitz-O’Keeffe marriage and wrote perhaps the most famous review of O’Keeffe’s work, hangs in the wings – as well as in a spooky portrait on the wall. (It’s by Stieglitz, of course.) It’s hard not to wish that the antagonizing Hartley would show up to add dimension and to flesh out the otherwise thinly drawn characters in Robertson’s play.

Yet Hartley is a reminder of why this work, despite its flatness, holds some mystique. Was there ever a more important time in American art history than the era of Stieglitz’s galleries, his legendary magazine and his own photography? A visit to this time – even with Robertson’s tin ear – is reason enough to go to this show. The details, though oddly arranged, are all there. It’s up to you to sit still for the portrait.

Acadia Repertory Theatre will present “Alfred Stieglitz Loves O’Keeffe” through July 11 at the Masonic Hall in Somesville. For information and tickets, call 244-7260. Alicia Anstead can be reached at 990-8266 and aanstead@bangordailynews.net.