Symbolism, Imagery, Allegory
From the very beginning of the book, Gypsy's hair is described as this long, luscious wonder. Her whole family appears invested in its growth, with her Granny and mother telling her when to wash it and how many times to brush it every night:
My hair was a great source of pride for her. She would tell everybody how many inches long it was and how many years she had been growing it, like it was one of her prize azalea bushes or something. To even hint at cutting my hair could spoil her day. (4.2)
The reason Gypsy's hair is so important to her mother is because before Amos died, he made her promise never to cut it. So Gypsy's hair represents one of the last links she and Love have to Amos—but at the same time, it also represents the burden of grief. So long as Gypsy keeps growing out her hair and hiding behind it, she can't really become her own person and forge her own identity. It is only when she chops it all off in a fit of rage that Gypsy can let go of the anger and pain she feels about her dad and finally move on with her life.