(FORTUNE Magazine) – The Ivy League degree, the Harvard MBA, and the fast-track management-training program are all useful accouterments. But what does a powerful woman need most? A larger-than-life mother. When we asked the women in our Power 50 to describe their childhoods, we heard a lot about kind, supportive fathers. But the women talked much more about unusual, influential mothers who became their role models and biggest fans.

Some of these older women were highly creative, like Carly Fiorina's mother, Madelon Sneed. She was an artist who "had an unbelievable zest for life," says Fiorina. "She taught me the power of keeping a positive attitude." Her mother began her career painting oil portraits and later moved to abstract work, using bold strokes and vibrant colors. Three years ago, when Fiorina was directing the Lucent Technologies spinoff at AT&T, she chose the Lucent logo--the bright-red ring of hand-drawn brush strokes--partly because it reminded her of her mother's paintings. Sneed died last December at 77. She saw her daughter make the cover of FORTUNE a year ago, as the most powerful woman in business, but didn't live to see her become CEO of Hewlett-Packard.

Other mothers of Power 50 women are pioneers. Avon President Andrea Jung's mother immigrated to the U.S. from Shanghai to study and then went on to a successful career as a chemical engineer. Jung, who has a younger brother, says her parents (her dad is an architect) urged both of their children to have careers. "They told me I could do everything my brother could," says Jung.

Meg Whitman's mother used to pile her children--Meg and her older sister and brother--into a Ford Econoline van and drive coast to coast or up the Alaskan highway during summer vacations. "We camped for three months. No hotels," says the CEO of eBay. In 1973, when Whitman was in high school, her mother traveled to China with actress Shirley MacLaine. Margaret Whitman was the Boston housewife in a delegation of "ordinary" American women whom MacLaine featured in a documentary, The Other Half of the Sky: A China Memoir. "Before the China trip, my mother told my sister to get a teaching degree--in case her husband couldn't support her," Whitman says. "When she came back from China, her perspective on women had changed completely. She told me, 'Go figure out what you want to do, and do it.'"

These mothers tended to be bold and unafraid to stand out. Pattie Dunn's mom, a former Las Vegas showgirl, "is a redhead in every way--mercurial, feisty, extremely funny, wacky," says the chairman of Barclays Global Investors. Her mother imposed no specific expectations on Pattie, except that she go to college, which neither Dunn's mother nor her late father, a vaudevillian, had done. Pattie graduated from Berkeley.

When Debby Hopkins was a girl growing up outside Detroit, her mother wrote the weekly social column for the Birmingham-Bloomfield Eccentric newspaper. Tagging along as photographer, Debby schmoozed at an early age with Henry Ford II and Lee Iacocca. "My mother loves to party, loves people," says the gregarious CFO of Boeing. As children, "we never had a box drawn around us like most kids do. We had no restrictions, not even curfews." Today, in her office, Hopkins displays a photo of her mother riding an alligator. "Whenever I feel like I'm up to my ass in alligators, I look at that picture and think, Just go for it," Hopkins says.

Other women on our list, like Amazon.com's Joy Covey, learned from mothers who gained strength through suffering. During World War II, Joan Covey, who is Dutch by heritage, lived in Indonesia (then the Dutch East Indies). When the Japanese invaded, she was sent to a prison camp for two years. She watched her own mother starve to death there. The hardship fostered an intense self-reliance, which daughter Joy has as well.

The mother of Paramount Pictures Chairman Sherry Lansing escaped from Nazi Germany at 17. When she was 32--and Sherry was 9--her husband died of a heart attack, leaving her with a real estate business in Chicago. "My father's brother came and offered to take over," Lansing recalls. "My mother told him, 'No, I can learn the business.' Even though she didn't have a college education or work skills, she was determined to not rely on a man." Her mother's ambition inspired Sherry, although a subsequent change--her mom remarried and quit working--sent a signal to Sherry that women couldn't combine marriage and a high-powered career. She chose a career. Margot Lansing died of cancer 15 years ago, when Sherry was 40. Six years later, Lansing resolved her angst and married director William Friedkin, the first man, she says, who hasn't tried to hold her back professionally.

The mother of Nancy Peretsman of Allen & Co. had a rough life, too, as a housewife in a difficult marriage. Says Peretsman: "When I turned 30, my mother took me to lunch and said, 'At 30, my life was over. At 30, your life is just beginning.' My mother had always felt trapped. She wanted me to have a career because she figured that was a way to get independence." Eventually Norma Peretsman followed her own advice: In her mid-30s she earned a master's degree and became a psychotherapist. She died of cancer three years ago, at 67.

If boys become men by breaking away from their mothers, girls become women by carrying part of their mothers with them. Sometimes, though, it takes a while for daughters to figure that out. Chase Manhattan's Dina Dublon says her success has come from having a rational mind and analytical skills, like her father. But she got something special from her mother as well. When Jenta Levin moved from Brazil to Israel in 1964 with her husband and 11-year-old Dina and two sons, she didn't know Hebrew or anyone in the country. Yet she settled in quickly. "She had this faith in herself that she could adjust without doing full research," Dublon says. "Her confidence was in her intuition." Today, in her new job as CFO at Chase, intuition is the very quality Dublon is seeking: "You never have certainty in global markets, so judgment and intuition are extremely important," she says. At a leadership course recently, Dublon took some psychological tests and learned that she is highly intuitive. "I have much more of my mother in me than I ever was willing to admit," she says.

Which, to a mother, is the best thing a daughter can say.