Final answer:
Alliteration in Walt Whitman's poem emphasizes the silence and shock of the daughters, creates a sense of unity and closeness, and highlights the overwhelming grief portrayed.
Step-by-step explanation:
The impact of alliteration in the lines from "Come Up from the Fields Father" by Walt Whitman is to enhance the emotional effect of the passage. The gathering of 's' sounds in alliteration emphasizes the silence and shock of the daughters, reinforcing the mood of the scene. The unity of sound provided by alliteration contributes to a feeling of closeness among the characters, strengthening the somber tone. Moreover, within the alliterative scheme, the focus on the word speechless highlights the overwhelming grief which leaves the characters unable to speak.