Lady Bird Johnson, the former first lady who championed conservation and worked tenaciously for the political career of her husband, Lyndon B. Johnson, died Wednesday, a family spokeswoman said. She was 94. Johnson, who suffered a stroke in 2002 that affected her ability to speak, returned home late last month after a week at Seton Medical Center, where she had been admitted for a low-grade fever. She died Wednesday afternoon at her Austin home of natural causes. Elizabeth Christian, the spokeswoman, said she was surrounded by family and friends. Even after the stroke, Johnson still managed to make occasional public appearances and get outdoors to enjoy her beloved wildflowers. But she was unable to speak more than a few short phrases, and more recently did not speak at all, Anne Wheeler, spokeswoman for the LBJ Library and Museum, said in 2006. She communicated her thoughts and needs by writing, Wheeler said. Lyndon Johnson died in 1973, four years after the Johnsons left the White House. The longest-living first lady in history was Bess Truman, who was 97 when she died in 1982. The daughter of a Texas rancher, she spent 34 years in Washington, as the wife of a congressional secretary, US representative, senator, vice president and president. The couple had two daughters, Lynda Bird, born in 1944, and Luci Baines, born in 1947. The couple returned to Texas after the presidency, and Lady Bird Johnson lived for more than 30 years in and near Austin. Former Republican President George H.W. Bush once recalled that when he was a freshman Republican congressman from Texas in the 1960s, Lady Bird Johnson and the president welcomed him to Washington with kindness, despite their political differences. He said she exemplified "the grace and the elegance and the decency and sincerity that you would hope for in the White House." "Like all Americans, but especially those of us who call Texas home, we loved Lady Bird," Bush said Wednesday. As first lady, she was perhaps best known as the determined environmentalist who wanted roadside billboards and junkyards replaced with trees and wildflowers. She raised hundreds of thousands of dollars to beautify Washington. The $320 million Highway Beautification Bill, passed in 1965, was known as "The Lady Bird Bill," and she made speeches and lobbied Congress to win its passage. "Had it not been for her, I think that the whole subject of the environment might not have been introduced to the public stage in just the way it was and just the time it was. So she figures mightily, I think, in the history of the country if for no other reason than that alone," Harry Middleton, the retired director of the LBJ Library and Museum, once said. Lady Bird Johnson once turned down a class valedictorian's medal because of her fear of public speaking, but she joined in every one of her husband's campaigns. She was soft-spoken but rarely lost her composure, despite heckling and grueling campaign schedules. She once appeared for 47 speeches in four days. "How Lady Bird can do all the things she does without ever stubbing her toe, I'll just never know, because I sure stub mine sometimes," her husband once said. Lady Bird Johnson said her husband "bullied, shoved, pushed and loved me into being more outgoing, more of an achiever. I gave him comfort, tenderness and some judgment - at least I think I did." She had a cool head for business, turning a modest sum of money into a multimillion-dollar radio corporation in Austin that flourished under family ownership for more than a half-century. With a $17,500 inheritance from her mother, she purchased a small, faltering radio station in 1942 in Austin. The family business later expanded into television and banking. "She was very hands on. She literally mopped the floor, and she sold radio time," daughter Luci Baines Johnson said of her mother's early days in business. When Johnson challenged Sen. John F. Kennedy unsuccessfully in 1960 for the Democratic presidential nomination, his wife was his chief supporter, although she confessed privately she would rather be home in Texas. His nomination as vice president on Kennedy's ticket drew her deep into a national campaign. She stumped through 11 Southern states, mostly alone, making speeches at whistle stops in her soft drawl. In his 1965 memoir, "Kennedy," JFK special counsel Theodore Sorensen recalled her "remarkable campaign talents" in the 1960 campaign. She was with her husband in Dallas on November 22, 1963, when Kennedy was assassinated, and was at his side as he took the presidential oath of office aboard Air Force One. In her book "A White House Diary," she recalled seeing Jacqueline Kennedy with her husband's blood still on her dress and leg. "Somehow that was one of the most poignant sights - that immaculate woman, exquisitely dressed, and caked in blood," she wrote. Suddenly, the unpretentious woman from Texas found herself first lady of the United States, splitting time between the White House and the Johnson family's 13-room stone and frame house on the LBJ Ranch, near Johnson City west of Austin. Her White House years also were filled with the turbulence of the Vietnam War era. The first lady often would speak her fears and hopes into a tape recorder, and some of the transcripts were included in the 2001 book "Reaching for Glory, Lyndon Johnson's Secret White House Tapes, 1964-1965," edited by historian Michael Beschloss. "How much can they tear us down?" she wondered in 1965 as criticism of the Vietnam War worsened. "And what effect might it have on the way we appear in history?" She quoted her husband as saying: "I can't get out. And I can't finish it with what I have got. And I don't know what the hell to do." Both daughters married while their father was president. Luci married Patrick Nugent, in 1966 at the Shrine of the Immaculate Conception in Washington. That marriage ended in divorce and she wed Canadian banker Ian Turpin in 1984. Daughter Lynda Bird married Charles Robb, later governor and US senator from Virginia, in a White House wedding in 1967. After she and her husband left Washington, Lady Bird Johnson worked on "A White House Diary," published in 1970. She also served a six-year term starting in 1971 as a University of Texas regent. She and her daughters remained active in her wildflower advocacy and with the LBJ Library in Austin after the former president's death in 1973. Into her 90s, Lady Bird Johnson made occasional public appearances at the library and at civic and political events, always getting a rousing reception.