The two floral envelopes of a flower; a collective term embracing both corolla and calyx as a unit; often used when it is not possible to distinguish one series from the other (as in most monocots) and the parts then called tepals.
n. (Gr. peri, around; anthos, flower) the outer whorl of floral leaves of a flower, when not clearly divided into calyx and corolla; collectively, the calyx and corolla, or either one if one is absent.
Formed of the calyx and the corolla, the perianth is the bulk of what we see as the flower. With petals in a vast array of colours and occasionally even coloured sepals, this structure is all show; it's shapes, colours, and patterns are geared at attracting insects and birds to aid in pollen transfer.