STEVE MARTIN’S SPLIT-LEVEL HUMOR

“Little Shop of Horrors” may be the first truly split-level film in several years. It offers maniacal farce on the main floor and sharp, satiric social commentary down below for those who want to look into the shadows.

That ingeniously contrived and ever-expanding flesh-eating plant can be seen not as a floral invader from some weedy galaxy in the future but as a symbol of any panacea, up to and including cocaine, that promises prosperity, health, happiness and an end to bathtub ring but delivers only a ruinous captivity.

The shop itself appears to be located on the Bowery, where you would expect to have trouble unloading wilted daisies for a cheap funeral. But the location makes possible a song called “Skid Row,” which is not a laff riot, and it allows, or forces, constant visual reminders of the frayed and gritty underside of society. The musical has been taken from the never-never land of satin, silks and glitter to the ever-ever mean streets of reality.

It does make for an original, bifocal viewing experience, which resembles a hearty shove at a party--friendly, but it nevertheless puts you off balance and sharpens the senses.

Amidst this duplexity, in an all-stops maxi-cameo, is Steve Martin as a wild-eyed and sadistic practitioner of painful dentistry.

In one long tug of war with molars and bicuspids, Martin, capped in an evil, skin-tight black wig, wipes out decades of efforts by the profession to make that ghastly drill sound like Beethoven and to prove that nothing will hurt a bit.

Like the movie as a whole, the laughs are split-level: uproarious, if you don’t have a dentist’s appointment in your foreseeable future, but otherwise inducing a cold sweat of memory or dread anticipation, or both.

Insofar as you can remain objective about what he’s up to, it’s a wonderfully expert performance by Martin, an assured mix of extravagant song, mime and acting. He plays second banana to a basso vine, but in his motorcyclist boots, he strides off with the humanoid honors.

Martin is good casting for the subtext exercise that “Little Shop” is. As a comedian, even as a stand-up buffoon with arrows ventilating his skull, he has somehow always conveyed that there was an intelligent chap lurking within the clown suit and eager to get out, not necessarily to play Hamlet but to be the comic actor, which is a bit beyond buffoonery. In his close-cropped silver hair, he doesn’t look comedic, but when you think about it, not many comedians do.

In “Three Amigos!,” which Martin co-authored and put together as executive producer, he was calculatingly trying to create an innocent comedy, an affectionate spoof of a Hollywood genre, the musical Western, in much the way he and Carl Reiner had kidded and saluted the private-eye film in “Dead Men Don’t Wear Plaid,” which is now frequently revived.

“I see so many comedies these days,” Martin said at lunch in a deli-restaurant he favors in Beverly Hills the other day, “and I say, ‘Wha-a-t?’ The youth comedies? Please. Which youth? Nobody does physical comedy anymore, like Lily (Tomlin) did in ‘All of Me.’ Almost nobody. Tom Hanks does. And there are exceptions. ‘Ruthless People’ was a terrific comedy. But with a lot of comedies, you look at the screen, you don’t laugh at it.”

“Three Amigos!” has taken its lumps for what are said to be its stereotyped and foolish Mexicans. Then again, the three gringos, played by Martin, Chevy Chase and Martin Short, are nothing if not fatuous and incompetent idiots, in flight from an idiot industry, 1930s Hollywood.

There are problems with “Three Amigos!,” but they have mostly to do with direction that opted for excess rather than subtlety and a camera that stayed curiously detached, as at the back of a theater.

Martin’s major scene in “Little Shop of Horrors” is with Bill Murray as a masochistic patient who is deeply into pain. The scene lacked a finish, Martin says, and he and Murray did 27 takes, under orders from director Frank Oz, simply to try something else. “We finally did the bit where I pat him on the back and find he’s trying to steal one of my tools. It worked.” It does.

Martin will have had four films out by the end of 1987: “Three Amigos!” and “Little Shop of Horrors,” “Roxanne” and “Trains, Planes and Autos.” “Roxanne” is a modernized version of “Cyrano de Bergerac,” in which Daryl Hannah will be Roxanne to his Cyrano and Shelley Duvall will complicate the proceedings. Fred Schepisi (“Plenty”) was the director. In it, Martin believes, the intelligent man and the clown suit find common cause. “I’ve seen a little bit of it,” he says, “and I think we’ve got a combination of tenderness and laughs, which we wanted. I like to work the ends of the spectrum.”

“Trains, Planes and Autos” is a John Hughes film in which Martin and John Candy will be two ill-met travelers trying to get to Chicago for Thanksgiving amid a blizzard and other difficulties.

For all the success of “The Jerk,” which has grossed more than $100 million, and “All of Me,” a critical and commercial success for him, Martin still considers “Pennies From Heaven” the high point of his career thus far, even though its reception was disappointing.

“It was learning how to dance; it was the education of an actor by Herb Ross; it was learning about those characters and their desperation, the nuances of their lives. I used to walk into those sets and believe . The farmhouse had a patina, as if it had been around forever. The costumes had pathos.”

It was a stretch, but not a risk, he insists. “If it was risk-taking, I hope it never goes away,” he says. “People who take risks don’t perceive them as risks, but as their life’s work. I never think about what I do as risky. I hope I never do.”