It's about an interracial relationship during the period between the end of Reconstruction and WWI, often referred to as "the nadir of American race relations", probably in the South. It's an inversion of the standard lynching trope, which usually would involve a black man and a white woman. Here, it's a white man (the narrator) who falls genuinely in love with a young black woman, and marries her despite the warnings of the black woman's family (the "silver-haired mama"). The relationship is not approved of by the community, and ultimately the woman is hanged on a tree, possibly on a tree where several blacks have been previously hanged ("in the shadow of the gallows of your family tree, a hundred hearts soar free"). When he refers to the tree pumping blood to "keep us young", he is referring to his family and the white community by extension, whose position is empowered and strengthened by the practice of lynching and racial oppression in general.
It's about an interracial relationship during the period between the end of Reconstruction and WWI, often referred to as "the nadir of American race relations", probably in the South. It's an inversion of the standard lynching trope, which usually would involve a black man and a white woman. Here, it's a white man (the narrator) who falls genuinely in love with a young black woman, and marries her despite the warnings of the black woman's family (the "silver-haired mama"). The relationship is not approved of by the community, and ultimately the woman is hanged on a tree, possibly on a tree where several blacks have been previously hanged ("in the shadow of the gallows of your family tree, a hundred hearts soar free"). When he refers to the tree pumping blood to "keep us young", he is referring to his family and the white community by extension, whose position is empowered and strengthened by the practice of lynching and racial oppression in general.