An oleander is a poisonous evergreen shrub that features beautiful white to red flowers. Aside from its literal connection to the plot of “White Oleander,” the plant is a metaphor for the character played by Michelle Pfeiffer a woman whose gorgeous blonde facade disguises her venomous nature.

The 44-year-old Pfeiffer has spent her career trying to counter the fact that her stunning looks often hinder her being taken as seriously as other maturing character actors. Even with three Academy Awards nominations to her credit, she is sometimes artistically overlooked. Recently, it’s her own fault for wallowing in maudlin pap like “I Am Sam” and “The Story of Us.”

But Pfeiffer may actually win a Best Supporting Actress Oscar this year for “White Oleander.” The role is a perfect match for the star. It’s a genuinely complex character who uses her timeless beauty as a defense mechanism, even as her psychological demeanor seems to shift on a whim.

As she explains, “Evil is tricky. Just when you think you know what it is, it changes form.”

In “White Oleander,” Pfeiffer plays Ingrid Magnusson, an eminent artist and single mom. Her daughter Astrid (newcomer Alison Lohman) is encouraged by her mother’s creative air but a little put off by her dominant methods. Smart, successful and comfortably arrogant, it’s clear Ingrid lives by her own set of rules.

Unfortunately, the state of California plays by other rules and convicts her of murdering a philandering boyfriend (Billy Connolly). With Ingrid in prison, the teenage Astrid begins a journey from one foster home to another, but always fettered by the manipulative reach of her mother.

Based on the bestseller by Janet Fitch, “White Oleander” is an episodic look at Astrid’s life. Each environment she is forced to connect with is screwed up in its own way, and every new home is run by a woman who becomes her surrogate parent.

The chameleonic Robin Wright Penn plays a former stripper who has become as addicted to Jesus as she was liquor and drugs. RenZellweger (“Bridget Jones’s Diary”) is an over-the-hill ingenue whose filmmaker husband is always finding excuses to leave her alone in their opulent house. Svetlana Efremova portrays a resourceful Russian immigrant who teaches Astrid the meaning of capitalism.

Inevitably, the imprisoned Ingrid finds fault with and seeks to dismantle whatever foster family Astrid stumbles into.

With her angelic face and ever-changing haircuts (from Barbie Doll to goth chick), Lohman delivers a convincing performance as a level-headed teen forced into situations where her persona is constantly being threatened. (It came as a surprise within the industry that Lohman earned top billing on the movie poster for “White Oleander” an unusual occurrence by Hollywood standards, given the clout of her co-stars. But her naturalistic work justifies the decision.)

Although the film (directed by TV veteran Peter Kosminsky) is guilty of skipping around with its narrative, it really struggles when dealing with Ingrid’s fundamental motivation. There is simply no reason offered why she would commit a murder.

It’s a huge step to go from being angry at an ex-boyfriend and following through with a premeditated poisoning. There isn’t even evidence that she planned to cover her tracks. Would a person who preaches such a free-spirited lifestyle welcome a sentence of 40-to-life in a federal penitentiary?

The only possible explanation is insanity, which the movie goes to great lengths to refute. Ingrid is painted as possessive and ruthless but never demented.

Also, it’s a mistake to put Connolly in the role of her boyfriend the film’s only casting mishap. The Scottish actor/comedian is such a dominant personality that he is wasted in what are essentially snippets of flashbacks viewed from a distance. His presence is a distraction because the audience keeps waiting in vain for him to take a more active part. He barely even speaks.

However, “White Oleander” ultimately comes off as an effective character study. It is compelling because the conflicts are interesting and the performances first-rate. Although the ending of the picture lacks a knockout punch the dramatic arc is reached earlier in an intensive courtyard confrontation between Ingrid and Astrid the movie thankfully avoids the urge to oversentimentalize the material.

After all, this isn’t a film about daisies or daffodils.