“An opulence of dahlias overran the box-borders, between cypresses that cut the sunshine like basalt shafts.”[1]
Mentioned while the unnamed first-person narrator is observing the gardens at the manor house before entering the Duchess’s apartments with the old man.
Dahlias are large and riotously colorful flowers. Here put at odds with cypresses that symbolize death and mourning, they become a symbol of vivid life. Concerning the contents of "The Duchess at Prayer", dahlias placed next to cypresses could be interpreted as are the Duchess's vibrant personality versus the confines of her marriage and living situation; striving life versus cold death. They also represent dignity as well as pomp[2]: The Duchess is retains her dignity and does not admit to having a lover. Pomp is seen in her love of elaborate gowns and her spending habits, creating a clever foreshadowing of two of her main personality traits.
[1] Wharton 1901, p. 2
[2] Boeckmann 2019