Enid Annenberg Haupt, 99, a publishing heiress whose passion for the glories of nature inspired her to give millions of dollars in support of public gardens, horticultural institutions and other green spaces in Washington, New York and around the world, died Oct. 25 at her home in Greenwich, Conn. No cause of death was reported.

Mrs. Haupt, daughter of publisher Moses L. Annenberg and sister of publisher and philanthropist Walter H. Annenberg, also donated millions to Memorial Sloan-Kettering Cancer Center and the Metropolitan Museum of Art in New York, the National Gallery of Art in Washington and numerous other institutions.

In Washington, she underwrote the Haupt Fountains on the Ellipse between the White House and the Washington Monument and made a gift of the four-acre Victorian-style garden on the south side of the Smithsonian Institution Castle, now known as the Enid A. Haupt Garden.

She also purchased River Farm, the 27-acre colonial plantation near Mount Vernon once owned by George Washington, which she donated to the American Horticultural Society. She became interested in the property when she found out the Soviet Embassy had considered buying it as a dacha, or summer home. That property belongs to the American people, she said.

"She was an unbelievably great lady who understood the importance of preserving great institutions, particularly great horticultural institutions," said Katy Moss Warner, president of the American Horticultural Society.

She made major gifts to various museums, including 13 pieces to the National Gallery of Art. Among the works were six bronze Alberto Giacometti sculptures, a Henry Moore sculpture and a Mark Rothko painting.

In New York, she rescued the venerable Victorian-style conservatory at the New York Botanical Garden in the Bronx shortly before the rotting wreck of a place was scheduled for demolition. Over the years she donated more than $34 million to the garden, which will receive a substantial gift from her estate.

"Enid A. Haupt was the greatest patron American horticulture has ever known," Gregory Long, president of the New York Botanical Garden, said in a statement. "Her philanthropy is unrivaled in our field."

In the 1990s, she donated works valued at $13 million to the Metropolitan Museum of Art. She also donated millions to maintain the gardens at the Cloisters, the Upper Manhattan institution that houses the Met's collection of art and architecture from medieval Europe.

Other beneficiaries included the National Wildflower Research Center, founded in Austin by Lady Bird Johnson, and Claude Monet's garden in Giverny, France.

"Nature is my religion," she often said. In 1982, she gave $1 million to the New York Public Library for the restoration of long-neglected Bryant Park and told the New York Times, "Books are the most important things in my life besides nature."

Enid Annenberg Haupt was born May 13, 1906, in Chicago, the fourth of Sadie and Moses Annenberg's eight children. She grew up in Milwaukee. The parents and children, seven girls and a boy, later moved to New York and then to Long Island, although Enid by then was attending Mount Ida Seminary in Newton, Mass.

"I was tall as a child. I weighed 90 pounds, and I had braids," Mrs. Haupt told the Times in 1982. "I always wanted to be accepted by my beautiful older sisters. I decided to be special. I vowed I'd learn a new word every day. I thought if I did, my sisters would have to say, 'What does that mean?' "

Mrs. Haupt's father, who spent time in prison for tax evasion in the 1930s, had bought a little publication called the Daily Racing Form in the 1920s. The track enthusiast's bible became the foundation of the family business, Triangle Publications, a publishing empire that Walter Annenberg sold to Rupert Murdoch in 1988.

The Annenberg family's holdings over the years included radio and television stations, the Philadelphia Inquirer, the Philadelphia Daily News and TV Guide, which Walter Annenberg founded in 1953.

He gave his sister a job as publisher, editor and editor in chief of Seventeen magazine, another family publication.

"Walter foisted the editorship on me when he was terminating a lady who had become a great nuisance," Mrs. Haupt told the Times in 1992. "I knew nothing about running a magazine, but my brother said, 'You can bring culture to the average working person who has not had your advantages.' "

She ran the perky teen publication from 1953 to 1970. She also wrote a syndicated column called "Young Living," dispensing advice on culture, as well as on fashion, beauty, boys and other, more immediate teenage girl obsessions.

She became interested in growing flowers, she said in a 1993 Los Angeles Times interview, when in 1936 she married Ira Haupt, a founder and partner in a Wall Street securities firm, who employed six gardeners at $60 a month at his New Jersey farm. She encouraged her new husband to find the workers better-paying jobs in defense factories, which he did, but that left her the only gardener at the farm.

Warner, who was working at the Horticultural Society of New York when she met Mrs. Haupt in the 1970s, recalled the magnificent pink begonias and the succulent echeverias that Mrs. Haupt raised in the greenhouses of her Greenwich home.

"I was so inspired that somebody could grow such beautiful, beautiful plants," she said. "Through those plants, you knew this was a woman who had great taste. She was an elegant, warm, generous person."

Her marriage to Norman Bensinger ended in divorce.

Ira Haupt, her second husband, died in 1963, and her brother died in 2002. There are no immediate survivors.

Enid A. Haupt funded the Haupt Fountains on the Ellipse and made a gift of the four-acre garden on the south side of the Smithsonian Institution Castle.