HOLLYWOOD — In "Pineapple Express," he plays a visibly unwashed hippie pot dealer on the run from mobsters: a THC-addled naif with a crinkly smile, a curtain of lank, dark hair and a heart of gold.

But don't get the wrong impression about James Franco just because of his spot-on performance in the most anticipated stoner action-comedy of the year. He's no dope, even though he smokes plenty onscreen.

To wit: Dude can almost carbon-date his experiences making certain movies by recalling what literature he was reading at the time.

In 2006, while filming the massive international blockbuster "Spider-Man 3," in which the actor plays Spidey's BFF turned arch-nemesis the Green Goblin, Franco was deep into the classical canon of Shakespeare, Chaucer and Milton — required reading for the creative-writing degree he was pursuing at the time.

"It took so long to set up the effects shots and get everything coordinated, it was perfect for doing homework," Franco said, chomping into a club sandwich at a Beverly Hills hotel.

Portraying Sean Penn's love interest in "Milk," director Gus Van Sant's biopic about slain San Francisco Supervisor Harvey Milk earlier this year, Franco stole many an off-camera moment to plow through the works of Thomas Pynchon.

And while filming the Judd Apatow-produced "Pineapple Express" — in which Franco's soulful, bromantic, type-shattering performance anchors the pot humor and surreal violence — it was all 16th-century Jacobean drama, all the time. "I can remember reading 'The Revenger's Tragedy' and 'Maid's Tragedy.' Stuff by Ben Jonson," Franco said.

His costar in the film, Danny McBride, recalled being impressed with the actor's ability to juggle Hollywood and academia.

"James just nailed it. He is hilarious," McBride said. "He was going to college full time while he was shooting the movie; he was in the makeup chair reading his homework. He would shoot nights and then go back to school the next morning."

Who knew? Here's a seemingly Serious Actor Type who devours serious books even while brooding and emoting in blockbusters and smaller indie fare alike.

At least that's how it adds up, taken with Franco's recent work, as well as his self-contained performances in 2002's "City by the Sea" opposite Robert De Niro and in the TV movie "James Dean," a biopic for which Franco won a best-performance Golden Globe for the title role.

But not so fast.

To hear the 30-year-old tell it, he's not really the Serious Actor guy he's reputed to be. Exhibit A: his career-altering choice to go to the comedy route.

The move was precipitated by a chance meeting two years ago with Apatow — his boss on the critically hailed but short-lived '90s sitcom "Freaks & Geeks" — who told the actor he "missed the funny Franco." Moreover, the comic mogul had a movie for him: a stoner action-adventure written by Seth Rogen and Evan Goldberg of "Superbad" fame.

Initially, "Pineapple Express" distributor Sony was skeptical about the "Spider-Man" franchise member playing it for laughs. Ultimately, Apatow — who produced such raunchy bros-and-bongs comedy hits as "40-Year-Old Virgin" and "Superbad" — convinced the studio Franco would be right for the film after the actor dialed in a funny screen test/cameo for the Apatow-produced maternity comedy "Knocked Up" and starred in a hilarious, self-skewering Web movie series, "Acting With James Franco," for www.funnyordie .com.