hair
髮 centers on hair, specifically the hair on a person's head.
髮 combines 髟 (hair) with 犮, which likely contributes the sound. The character is the traditional form of 髪.
The top component 髟 represents long hair, and the bottom 犮 looks like a person with flowing hair. Together they make 髮, meaning hair.
For ハツ, imagine a hat sitting on top of a head of hair: hat -> ハツ, and the hat covers the 髮.