When Lady Bird Johnson walks among wildflowers at the home of an Island friend near Watcha Pond, she steps lightly and speaks gently. Indeed, the former First Lady is home on the Vineyard or anywhere in the world among these perennials that have touched her life from childhood days in east Texas to White House years in the nation’s capital. Even today, more than 20 years after Mrs. Johnson’s departure from the White House, she devotes a central part of her busy life to the preservation of wildlife and beauty in America.