As Ivy, a rootless Los Angeles teenager with blond, tousled hair and an ivy- wrapped crucifix tattooed on her thigh, Drew Barrymore is this year's model of the all-American junior vixen the haughty girl-child who drives men wild. Barrymore, the adorable tot from E.T., has grown up into a startlingly salacious young woman. With her alabaster skin and a face that's all smooth, dimply, little-girl curves, she's a Pre-Raphaelite waif who seems to cry out for protection. But then she flashes her dark, prematurely come-hither eyes and lets her lips curl into a knowing smirk. ''However dirty your thoughts are,'' she seems to be saying, ''I'm already way ahead of you.''
A few years ago, Barrymore's widely reported fast-lane adventures cemented her offscreen reputation as Hollywood's bad girl of the moment. (Diane Lane, we hardly knew ye!) In Poison Ivy, she doesn't show a lot of craft as an actress, but she isn't slumming, either. Her fresh-yet-jaded sultriness is alive on screen. What makes Ivy an up-to-the-minute variation on the traditional Hollywood Hills Lolita is that she's a post-Valley Girl, post- Madonna temptress. Her nose ring, her baby-hooker outfits, her attitude of leering erotic knowingness it has all been officially sanctioned by the media. She's part of a commercially rebellious youth culture in which being a ''slut'' really means emulating the edgiest role models on MTV.
Barrymore is a vivid presence, but Poison Ivy, I'm afraid, isn't much of a movie. It's an arty exploitation thriller, all sleek, machinelike surface, with by-the-book ''moody'' cinematography meant to camouflage a ridiculous plot. In the tradition of Hollywood teen-rebel fantasies, Ivy meets Cooper (Sara Gilbert, of Roseanne), a buttoned-down girl who secretly yearns to cut loose. With her small eyes and thin-lipped grimace, Gilbert hints at the quiet frustration of being a plain-Jane teenager, but she also wears the same quizzical, sourpuss expression in nearly every scene.
For a while, the movie seems to be on to something: the quick, confessional intimacy of modern teen friendships. Then Ivy moves into Cooper's big, luxurious house and meets her folks, who might as well have ''Dysfunctional Parental Units'' stamped on their foreheads. Cooper's suicidally depressed mother (Cheryl Ladd) lies in bed, scarfing Percodan and breathing through an oxygen mask. Her father (Tom Skerritt), a TV-station general manager who writes moralistic editorials, skulks around like an extra from Night of the Living Dead. Ivy flirts with him, but not because she's turned on by this middle-aged geezer (or even by the thought of manipulating him). No, she just wants a family of her own. She's a jailbait version of Rebecca De Mornay's demonic baby-sitter in The Hand That Rocks the Cradle.
Whatever reality there is to Poison Ivy quickly goes out the window, as Ivy attempts to replace Cooper's mom, and to replace Cooper as well. Instead of tapping the dark eroticism of a teenager who makes herself a tease in order to establish her power, the film opts instead for a kind of official, TV-movie kinkiness. Even the casual physical closeness between Cooper and Ivy gets tricked up into ''lesbian'' nuzzling. Overtones are about all there is to Poison Ivy. The movie isn't smart, but it never achieves true sleaziness either.