A flower is a modified shoot, meant for reproduction in angiosperms. A typical flower has a stalk called pedicel and four different kinds of appendages arranged in successive whorls on the swollen end of the axis called thalamus. The outermost whorl is the calyx, and consists of sepals. The next inner whorl is the corolla and consists of petals. The third whorl is the androeium which is composed of stamens. The fourth and innermost whorl is the gynoecium which is composed of carpels. The calyx and corolla are called accessory whorls and the androeium and gynoecium are called essential reproductive whorls.