Quincuncial /(?)/

Quin·cun·cial

Quincuncial
  1. Having the form of a quincunx.
  2. Having the leaves of a pentamerous calyx or corolla so imbricated that two are exterior, two are interior, and the other has one edge exterior and one interior; as, quincuncial æstivation. (Bot.)

Phrases & Compounds
Quincuncial phyllotaxy
an arrangement of five leaves in a spiral, each leaf two fifths of a circle from the next.