quincuncial

Adjective

quin=cun=cial

CIDE DICTIONARY

quincuncial, [L. quincuncialis, from quincunx. See Quincunx.].

Having the form of a quincunx. [1913 Webster]
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. [1913 Webster]

Quincuncial phyllotaxy (Bot.), an arrangement of five leaves in a spiral, each leaf two fifths of a circle from the next.