Knapweed (Centaurea montana) reproductive parts. Surrounding the reproductive parts (centre) are the flower's petals (purple). At the very centre of the flower are the female reproductive parts, collectively called the pistil (dark purple/pink). The pistil is composed of one or more carpels. Each carpel is made up of a stigma (pink, centre) attached to a long tube (style, purple), which links the stigma to the ovary (female sex cell, not seen). The male reproductive parts (stamens) surround the pistil. Each stamen is made up of a long filament (black tube) tipped with an anther (pink, blurred), which discharges pollen (male sex cells).