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. The petals of a flower are referred to collectively as the corolla. Just inside the petals is a whorl of stamens. Each stamen is composed of a thin stalk, called a filament, and a saclike anther, where meiosis occurs to form microspores that develop into pollen grains. Each pollen grain produces two cells surrounded by a though outer wall.