*quincuncial*

[ L. quincuncialis, from quincunx. See Quincunx. ] [ 1913 Webster ]

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

2. (Bot.) 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. [ 1913 Webster ]