Janie's most noticeable characteristic is her hair; it's long, straight, and representative of her blended racial heritage. She's a beautiful woman who is admired and desired by men throughout the novel. Her beauty also makes her feel like people don't see her for herself at times.

The first physical description the reader gets of Janie is as she's walking and people are watching her. Zora Neale Hurston writes:

The men noticed her firm buttocks like she had grapefruits in her hip pockets; the great rope of black hair swinging to her waist and unraveling in the wind like a plume; then her pugnacious breasts trying to bore holes in her shirt.

Throughout the book, references are made to Janie's hair. It's long, smooth, and straight. It's mentioned repeatedly when the author refers to her. When she returns after burying Tea Cake, people wonder why a woman in her 40s has such long hair that they say is worn like a young girl's.

One of the ways that Janie can tell there's a problem between her and her husband is that he pays less attention to her hair. Hurston writes, "He had ceased to wonder at her long black hair and finger it." As she gets older, her hair stays the same even though other parts of her have changed. After Jody dies, she examines her hair in the mirror:

She tore off the kerchief from her head and let down her plentiful hair. The weight, the length, the glory was there. She took careful stock of herself, then combed her hair and tied it back up again.

It's the main focus on how Janie looks throughout the novel.

One thing that I think is also important to note about Janie's hair is that once Jody dies, one of the first things Janie does is to remove the head wrap and let down her hair. 

Janie's most noticable physical characteristic is her straight hair, which she takes great pleasure in showing off. Janie's hair is symbolic not only of her power, but it is what makes her different and sets her apart. Characters like Jody recognize the power of her hair; it is why he forces Janie to bundle it up and keep it hidden under a rag. Jody fears the individuality and independence Janie's hair represents.