Lucy Braun was born in Cincinnati, Ohio, and, though she traveled extensively, remained there for the rest of her life as first a student, and later a professor at the University of Cincinnati. She earned a PhD in botany from the university in 1914, and taught botany and geology there continuously until being appointed Assistant Professor of Botany in 1923. In 1950, she became the first female president of the Ecological Society of America, where an award for students carries her name.
Braun is best-known for her landmark book, Deciduous Forests of Eastern North America (1950), and she published extensively on botany and plant ecology.