Quincuncial
Pronunciation : Quin*cun"cial
Etymology : [L. quincuncialis, from quincunx. See Quincunx.]
Definition : 1. Having the form of a quincunx.
2. (Bot.)
Defn: 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 ?stivation. Quincuncial phyllotaxy (Bot.), an arrangement of five leaves in a spiral, each leaf two fifths of a circle from the next.
Source : Webster's Unabridged Dictionary, 1913