Wistaria is a clinging flower that is linked to feminine sexuality in Rosa Coldfield's narration of her imagined connection with Charles Bon. Quentin seems to notice the wistaria when he visits Rosa in the beginning of the book, and wistaria appears in Jason Compson's discussion of Sutpen (entwined with cigar smoke).
The Sutpen house and Property (Sutpen's Hundred)
The rise (and decay) of Sutpen's home near Jefferson mirrors the fortunes of his family, beginning as a masculine domain with no carpet, windows, or mattresses, becoming a more formal and decorative estate when he acquires a wife, and falling into disrepair during his absence and after his death.
Wash Jones and the Borrowed Scythe
Wash lives on Sutpen's land and works to maintain and defend Sutpen's daughter and home in his absence. Wash borrows the scythe, apparently, to help harvest food for Sutpen himself. It becomes a symbol of "reaping what you sow," as a reaping tool that Wash uses to murder Sutpen.
Faulkner, for good or ill, propagates a racist conception of "negro blood" as a kind of curse or evil that, when blended with Sutpen "blood" in Clytie, becomes even more sinister than the original. Part of the curse that falls on the last of Sutpen's family, Jim Bond, is his "negro blood," despite Shreve's suggestion that the "blood" of "African kings" will soon be common at Harvard.
The Cold Air at Harvard
The cold air at Harvard is a metaphor for Quentin's displacement and ill preparation for the world outside of Mississippi, and a way of showing how much stronger Shreve is, both in body and spirit. Mr. Compson's letter about Rosa's funeral also links the cold with death and with exposure (and preservation).