Respect Your Instincts
Ultimately, the most important theme of this poem is a piece of advice: respect your instincts. This is an overarching theme encompassed across the entire body of work of the poet. She is a nature writer who celebrates the instinct of the natural world and is constantly pushing humanity to be more like animals. The poem starts out as a logical debate over the pros and cons of the issue at hand, but the final decision is made solely on the level of emotions and gut feelings. Which is just another name for instinct.
The Bondage of the American Dream
The mother and daughter who share the home in this story are portrayed as not being in a state of financial independence. They are certainly not at risk of losing everything in the blink of an eye and can even, in fact, afford to pay off their mortgage entirely if they sell the tree for lumber. They are like the overwhelming majority of Americans who are forced to make decisions on a transactional basis that should be made completely on the basis of other concerns. Allusive references in the text make this quite specifically about the pursuit of the American Dream, and the circumstances of the two women make it clear that this pursuit has left them in bondage to the dark side of this dream. That the decision to keep the tree is specifically made on the basis of a dream the daughter has only further intensifies this thematic connection.
Family
The poem begins with the assertion by the daughter that she and her mother are engaged in a debate. This statement naturally creates the initial presumption that the debate is taking place between the two women. It is quickly revealed that this is not the case, but the semantic trickery of that opening line is highly suggestive of the reality that stories about mothers and daughters generally tend to build their dramatic conflict from an antagonistic relationship. In this poem, the mother and daughter are presented as a totally unified front working together toward a common purpose. References to roots, the history of immigrant ancestors, the house itself being passed down through generations, and the tree itself (a symbol of ancestral lines) all serve as reminders of the importance of family.
