The title of the poem, "Strange Fruit," is a metaphor for the lynching of African Americans in the United States. The title is a reference to the bodies of African Americans hanging from trees, which were a common sight in the South during the Jim Crow era. The title is meant to evoke a sense of horror and injustice, and to draw attention to the brutality of lynching.
The phrase "blood on the leaves" is a reference to the blood of the victims of lynching, which would often be left on the leaves of the trees where the bodies were hung. The phrase "at the root" is a reference to the systemic racism and oppression that was the root cause of the lynching of African Americans. It is also a metaphor for the deep-seated hatred and prejudice that was the foundation of the Jim Crow era.