The Bell Jar Passage:
The tears came in a rush, then, and while the sailor was holding me and patting
them dry with a big, clean, white linen handkerchief in the shelter of an American elm, I thought what an awful woman that lady in the brown suit had been, and how she, whether she knew it or not, was responsible for my taking the wrong turn here and the wrong path there and for everything bad that happened after that.
Elm – Noun
Definition: any of a genus (Ulmus of the family Ulmaceae, the elm family) of usually large deciduous north temperate-zone trees with alternate stipulate leaves and fruit that is a samara
Now that I know what an Elm is it is clear to me that Esther was taking shelter under a large tree, and can now visualize it.
://www.merriam-webster.com/dictionary/elm