whorl

noun

Circle of flowers, parts of a flower, or leaves arising from one point; verticil. An arrangement of appendages, such as branches or leaves, such that all are equally spaced around the stem at the same point, much like the spokes of a wheel or the ribs of an umbrella.
In shell, any complete (360o) coil or exposed surface of a complete coil (drawing). First-formed and smallest whorls begin at apex and increase in size until last whorl (body whorl). The line forming border between two adjoining whorls is termed a suture.