One Edward Norton performance is often enough reason to see a movie, so it comes as no surprise that the prospect of two — he plays twins — is very much the main attraction, and reward, of “Leaves of Grass.” That aside, this latest feature as writer-director by thesp Tim Blake Nelson (who also plays a supporting role) is a mixed bag of often mismatched ideas. Tale of brothers involved in a dangerous, major pot growing operation isn’t exactly an arthouse item or a mainstream one, either, with good ancillary prospects but tricky placement ahead theatrically.

The pic is curiously reminiscent of Steven Gyllenhaal’s 1998’s “Homegrown” — not only because it places another starry cast in the same basic setting, but because its mix of hayseed stoner hijinks, no-joke violence, family drama and other elements likewise fails to cohere in either script or execution. Though it, too, eventually becomes a bit of a mess, “Leaves” is the better film, thanks to an opening reel in which Norton as straight man finds an ideal comedy partner in Norton as goofus.

Bill Kincaid (Norton) is a Brown U. professor of classical philosophy who has students swooning to his Socrates lectures and Harvard begging for him to come start his own institute there. No one would ever guess he was once a rural Oklahoma good ol’ boy, which is just how he prefers it, having cut ties long ago with the agents of his formative years of chaos: aging-hippie mother Daisy (Susan Sarandon) and 35-going-on-15 brother Brady (Norton again). As Brady ruefully tells Daisy, “One of us would have to die for him to come home.”

Next comes that call: Bolger (Nelson), Brady’s business partner, informs Bill his estranged twin has died in a crossbow mishap. Upon reluctant arrival, however, Bill finds his sibling very much alive and unapologetic about the ruse; he did what he needed to secure a family reunion.

Besides, Brady needs his doppelganger (give or take a circa-1972 haircut) to pose as him, providing an alibi when he goes to settle some potentially hazardous negotiations with a shady Tulsa businessman (Richard Dreyfuss). (Improbably, no one hereabouts seems to know Brady has a twin, though both grew up in the area.) Naturally, the plan goes awry, though not before Bill finds a local love interest in Janet (Keri Russell), a poet and high school English teacher.

So long as it’s Norton vs. Norton, “Leaves of Grass” is a pleasure, with master pot-farm horticulturalist Brady — according to Mom, an even higher-IQ genius than Bill, albeit one who never thought to gussy up his redneck speech, look or lifestyle — playing a delightful pain in the neck to his uptight bro.

Unfortunately, midway through, the plot kicks in. Nelson’s script isn’t blackly comic or deep enough to successfully accommodate the introduction of jarring violence. A subplot involving Josh Pais as a Jewish orthodontist moving his family to Oklahoma doesn’t quite work; nor do scenes with Dreyfuss (sporting an unfortunate stab at an Oakie-Catskills accent) as a Jewish mobster, while the romance with Russell feels perfunctory. Eventually, “Grass” reaches for tragedy, forgiveness and personal catharsis — but it all feels forced after the pic’s earlier, relaxed comic rhythms.

Nelson himself provides the most valuable support in the colorful if variable cast. Tech and design contributions are unassertive but solid.

Leaves of Grass

  • Production: A Millennium Films and Langley Films presentation of a Class 5 Films production. (International sales: Nu Image, Los Angeles.) Produced by Tim Blake Nelson, Edward Norton, Bill Migliore, John Langley, Elie Cohn, Kristina Dubin. Executive producers, Avi Lerner, Danny Dimbort, Trevor Short, Boaz Davidson, David Koplan, Stuart Blumberg, Eric Gitter. Directed, written by Tim Blake Nelson.
  • Crew: Camera (color), Roberto Schaefer; editor, Michelle Botticelli; music, Jeff Danna; music supervisor, Randall Poster; production designer, Max Biscoe; costume designer, Caroline Eselin; art director, Rob Simons; set decorator, Marina Nay; sound (Dolby Digital), Steve C. Aaron; supervising sound editors, Douglas Murray, Jonathan Null; assistant director, Michael Moore; casting, Avy Kaufman. Reviewed at Toronto Film Festival (Special Presentations), Sept. 14, 2009. Running time: 104 MIN.
  • With: Bill/Brady Kincaid - Edward Norton Janet - Keri Russell Pug Rothbaum - Richard Dreyfuss Daisy - Susan Sarandon Ken Feinman - Josh Pais Colleen - Melanie Lynskey <b>With:</b> Pruitt Taylor Vince, Maggie Siff, Lee Wilkof, Steve Earle, Lisa Benavides, Lucy DeVito, Ty Burrell, Randall Reeder, Tim Blake Nelson.
  • Music By: