Final answer:
The section of curl between the scalp and the first turn of the roller is known as the stem, which is crucial for hair's mobility and style direction.
Step-by-step explanation:
The section of curl between the scalp and the first turn of the roller is called the stem. When styling hair, the stem of a curl determines the hair's mobility and direction. Wrapping the hair around the roller creates the base which determines the volume, and the circle represents the part of the hair that is wound around the roller. Understanding the anatomy of a hairstyle, such as the hair stem, can lead to more precise and desired hairstyling outcomes.