Environmentalist Marjory Stoneman Douglas, the feisty, tireless grande dame of the Florida Everglades who led the fight to preserve her "river of grass," died May 14 at the home in Miami where she had lived since 1926. She was 108.

Mrs. Douglas had been slowed in recent years by blindness, hearing difficulties and other problems. "The years caught up with her," William T. Muir, a lawyer and family friend, said when asked the cause of death.

For many, Mrs. Douglas was more than an environmentalist. She was considered the authority on the Everglades' delicate ecosystem, which is home to plants and animals found nowhere else.

In 1947, she helped lead the successful push to have nearly 1.6 million acres designated as Everglades National Park. That same year, she published her book "The Everglades: River of Grass," the first attempt to put the history of the Everglades into one volume.

Until then, the Everglades was considered a wasteland to be conquered and used for farming, and state policies encouraged drainage and development. The book's title referred to the fact that the Everglades is really a wide river of shallow water flowing slowly southward across a low, grassy plain.

The book combined scientific findings and traditional lore. "The clear burning light of the sun pours daylong into the saw grass and is lost there, soaked up, never given back," Mrs. Douglas wrote. "Only the water flashes and glints. The grass yields nothing."

Long past an age when most people slow down, Mrs. Douglas continued to speak out on behalf of the imperiled South Florida region damaged by rapid development.

The celebration of her centennial in 1990 was marked by a series of events, including book signings, banquets and media interviews.

Her honors included a special conservation award named for her, an act of the legislature in her name and several Marjory Stoneman Douglas schools and parks. The high-rise gold glass building in Tallahassee that houses the state Department of Natural Resources is named for her. In 1993, President Clinton awarded her the Presidential Medal of Freedom.

Even when others insisted the battle over the Everglades was lost, Mrs. Douglas refused to give up.

"It's not too late, or we wouldn't be working. We simply cannot let everything be destroyed. We can't do that, not if we want water. We've got to take care of what we have," Mrs. Douglas said in a 1990 interview.

In recent years, state and federal governments have authorized multimillion-dollar projects to help restore and protect what remains of the Everglades, including a 1994 state law called the Everglades Forever Act. But drought and pollution, particularly runoff from the region's sugar farms, have continued to keep the long-term fate of the region in doubt.

Mrs. Douglas was born in Minneapolis and raised in Massachusetts. She moved to Miami in 1915 to obtain a divorce from her husband of one year and get reacquainted with her father, Frank Stoneman, the first editor of the paper that eventually became the Miami Herald.

Mrs. Douglas, educated at Wellesley College, went to work for her father and soon began her defense of the Everglades, angering developers and politicians with her editorials against overdraining the wetlands.

She worked overseas during World War I for the Red Cross. After the Armistice, she returned to daily newspaper work through the mid-1920s and then quit to do freelance writing. Besides "River of Grass," which continues to sell well, Mrs. Douglas wrote several youth-oriented books, a history of Florida and, more recently, a biography of environmentalist-novelist W.H. Hudson.

She had no close surviving relatives. CAPTION: President Clinton awarded Marjory Stoneman Douglas the Presidential Medal of Freedom in 1993.