corolla

The corolla is the collective term for the petals of a flower, the inner whorl of the perianth. It is usually more conspicuous than the outer calyx and is often colored and scented to attract pollinators. The corolla sits inside the calyx, and together the two whorls form the complete perianth.

The petals may be free (distinct) or fused, producing a corolla tube with lateral lobes. Corolla symmetry may be actinomorphic (radially symmetric) or zygomorphic (bilaterally symmetric). The upper lobes or the entire rosette can bear nectar guides. The corolla develops from petal primordia in the floral meristem; fusion occurs when petals grow together at their bases.

The corolla is functionally important in pollination biology, guiding pollinators to the reproductive organs and sometimes providing nectar. Color, shape, fragrance, and ultraviolet patterns influence pollinator behavior. In wind-pollinated species, the corolla is reduced or absent.

Etymology: corolla from Latin corolla, "little crown" or garland, referring to its crown-like appearance in many flowers.

Taxonomic note: Corolla morphology varies widely across angiosperms and is a key character in classification. Flowers in some families, such as those with tubular corollas, are specialized for certain pollinators.