Symbolism, Imagery, Allegory
The Sojourner has one heck of a story.
Everything begins with Louvinie. Louvinie comes from a prominent family of West African soothsayers, specializing in "the weaving of intricate tales with which to entrap people who hoped to get away with murder" (1.3.29). Creepy.
In America, Louvinie puts her skills to good use by entertaining the slave master's kids with her spooky stories. That is, until one of her stories scares one boy so badly that he has a heart attack and dies. When you think about it, Louvinie is still fulfilling her family's tradition...
After this, Louvinie's tongue is cut out as punishment. That'd be rough for anybody, but we'd imagine it's especially brutal for a storyteller like Louvinie. Instead of sinking into despair, however, she prepares her tongue in a strange, mystical way and plants it beneath "a scrawny magnolia tree on the Saxon plantation" (1.3.37). As the tree grows, so do all sorts of stories and folklore about the tree's magical properties. In a way, Louvinie's amazing ability for storytelling lives on through the Sojourner.
Then, the unthinkable happens. During the riots following Wild Child's funeral, "the only thing" that the students "managed to destroy was The Sojourner" (1.3.55). This reflects how many of the college activists in the Movement lack the proper perspective to do good. Instead of taking out their rage on the people who deserve it, they cripple themselves by destroying something near and dear to their hearts.
As Black Elk (a famous Native American leader) states in the book's foreword, "there is no center any longer, and the sacred tree is dead." The Sojourner—and the stories and traditions associated with it—is gone. But there's still hope. Meridian becomes that new center, transforming the lives of individuals just as the Sojourner did for her. Over the course of the novel, she has grown into something special and new, like the "tiny branch [...] growing out of one side" of the Sojourner's stump (3.33.9).