Calyx

Calyx is a term used in biology with several related but distinct meanings. In flowering plants, the calyx is the collective term for the sepals, the outer floral whorl that protects the developing bud. The sepals are typically green and leaflike, but in some species they are colored or petaloid. The calyx, together with the corolla, makes up the perianth. Sepals may be free or fused, producing a calyx tube or cup; the lobes may be 2–5 or more. The calyx can persist after flowering, providing protection for developing fruits or serving as a part of the fruit in some taxa.

In anatomy, the term calyx refers to a funnel- or cup-shaped cavity. The most familiar example is the renal calyx, a chamber in the kidney that collects urine from the collecting ducts. The minor calyces drain into the major calyces, which connect to the renal pelvis and ureter. The word is also used in other contexts to denote cup-like structures in various organisms.

Etymology: calyx derives from Latin calyx, from Greek kalux, meaning "cup" or "husk." In botany the term is primarily used for the sepal-based outer envelope of a flower, and in anatomy it refers to hollow, cup-shaped cavities.