IN 1990, on the twentieth anniversary of Earth Day, I asked author and activist Marjory Stoneman Douglas to comment on the state of the environmental movement. “There’s more people interested in the environment these days,” she quipped in her proper Julia Child voice. “Trouble is, there’s more people!”

It was vintage Douglas: brief, blunt, and funny. She was 100 years old then, and lived to be 108 in her little house in Miami’s Coconut Grove. Her long life and work on behalf of Florida’s Everglades is the subject of a new biography, An Everglades Providence. It’s an exhaustive look at Douglas’s life, with detailed forays into the history of environmental politics.

Douglas literally grew up with Florida. Biographer Jack E. Davis notes that when she moved south from New England in 1915, she was twenty-five and Miami was just nineteen. She didn’t get involved in the movement to save the Everglades until she was seventy-nine years old — twenty-two years after she wrote the 1947 book Everglades: River of Grass. She was a writer first and activist second.

River of Grass was one volume in Farrar and Reinhart’s Rivers of America Series. Douglas was already an established writer, published in the Saturday Evening Post and the Miami Herald (which was founded by her father, Frank Stoneman), when an editor for the series approached her about writing a book about the Miami River. She countered with another idea: the fascinating Everglades, she said, were actually a sixty-mile-wide river of grass. Before River of Grass, most Americans saw the Everglades as a swamp in need of draining. Her eloquent descriptions changed that, adding fuel to those working to make the great wetland into a national park.

Anyone looking for minute details of the politics around saving the ‘Glades will find them in Davis’s book. He paints an affectionate portrait of the quirky Douglas, a Wellesley graduate who lived most of her life alone as a woman of letters. (She was married briefly to a Mr. Douglas, who was jailed as a con man — curiously, she kept the name for the rest of her life.)

President Bill Clinton awarded Douglas the Presidential Medal of Freedom when she was 103. She remained a tough taskmaster. Davis writes, “Douglas never overestimated her impact. ‘No one is satisfied with their life’s work,’ she said during the week she turned 104. ‘There is always the need to carry on. The most important thing is to prepare competent people to follow you.'”