The peduncle may terminate in a single flower or a cluster of flowers known as an inflorescence. The tip of the peduncle enlarges to from a receptacle that bears some for all of the flower parts. A flower that has all four parts is said to be complete, whereas an incomplete flower lacks one or more of these four parts. A flower with both stamens and carpels is said to be perfect, whereas an imperfect flower has stamens or carpels, but not both. Sepals, which make up the lowermost and outermost whorls on a floral shoot, are leaf-like in appearance and often green.
Sepals cover and protect the other flower parts when the flower is a bud.
As the blossom opens, the sepals fold back to reveal the more conspicuous petals. The collective term for all the sepals of a flower is the calyx. The whorl just above the sepals consists of petals, which are broad, flat, and thin but vary in shape and are frequently brightly colored. Petals play an important role in attracting animal pollination to the flower. Sometimes petals are fused to form a tube or other floral shape.