Reproductive Parts

Flower is the reproductive part. It is highly condensed and modified shoot meant for sexual reproduction.

• A typical flower consists of four whorls. The outer two whorls are called accessory or helping whorls and the inner two whorls are called reproductive or essential whorls.
• Accessory whorls: There are two accessory whorls, calyx and corolla. The calyx is made up of sepals, which are generally green in colour. The corolla consists of petals which are generally bright in colour and often larger in size. Accessory whorls initially give protection to the developing essential whorls. The corolla attracts insects and serves as an important tool for pollination.
• Reproductive whorls: There are two reproductive whorls, androecium and gynoecium. The androecium is the male reproductive organ and is made up of stamens. Each stamen has three parts-filament, connective and anther. Filament is a thin, cylindrical, sterile stalk bearing anther lobes at the tip. Connective is the tissue, which joins the anther lobes to the filament. Anther contains large number of pollen grains. Later, during the development, pollen grains produce male gametophytes which in turn produce male gametes. The gynoecium is the female reproductive organ and its unit is carpel. A typical carpel is having stigma, style and ovary as its three parts. Ovary is the fertile portion in which ovules are present. On the inner wall of the ovary there is a parenchymatous tissue known as placenta. It bears one or many ovules. Ovule is having embryo-sac in which egg cell or female gamete is present.
• After two embryological events, pollination and fertilization, flower is changed into fruit and the latter sets seeds. The ripened ovule with embryo is called seed. The ripened ovary with ovules constitutes fruit and thus seeds are present inside fruit, hence called angiosperms. Seed consists of seed coat and embryo.
• Embryo is, in fact, a miniature plant. Seeds after dispersal and germination, give rise to new diploid sporophytic plants of angiosperms.