Symbolism, Imagery, Allegory
Throughout Meridian, hair is used to represent the way that white standards of beauty are thrust upon minorities in America.
Basically, pop culture inherently favors white hairstyles over black hairstyles. As touched on by documentaries like Good Hair, many African-Americans feel pressured to conform to white hairstyles because society places a higher value on long, straight hair.
This comes up a lot with Lynne. As Lynne's relationship with the black community grows more tense, Lynne begins consciously "taking down and combing her hair" whenever "she found herself around black women," passive-aggressively flaunting the "treasure they could never have" (2.22.76). Lynne is bummed about her life, and the only way she can make herself feel better is by making others bummed about theirs.
Being intellectuals, Meridian and Truman can see right through this. Earlier in the book, Truman refuses to take a picture of Lynne with some neighborhood kids because the sight of them "taking turns combing her hair" hits a little too close to home (2.16.1). Similarly, Meridian highlights the hypocrisy of a Saxon College administrator by pointing out her "long, processed, and lavender" hair (1.3.5). While Truman and Meridian are by no means exempt from societal pressure like this, they at least have the wisdom and education to see through it.