That pattern is called a phyllotaxis. It describes the arrangement of leaves on a stem.

Specifically, the circular pattern you're describing is called spiral phyllotaxis.

There are different types of phyllotaxis, but spiral phyllotaxis is the most common. It can be further categorized based on the number of leaves per turn around the stem:

* Distichous: 2 leaves per turn (e.g., grasses)

* Tristichous: 3 leaves per turn (e.g., sedges)

* Pentastichous: 5 leaves per turn (e.g., apple trees)

The arrangement of leaves in spiral phyllotaxis is determined by the Fibonacci sequence, which ensures that each leaf receives maximum sunlight exposure.