Sexual Reproduction in Flowering Plants

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Angiosperms show alternation of generations between a diploid sporophytic phase and a haploid gametophytic phase. The sporophytic phase is (2n) and develops from the diploid zygote. The gametophytic p…

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Flowers carry the male and female reproductive organs of angiosperms. Stamens produce pollen grains, and carpels contain ovules. Because pollination, fertilization, seed formation, and fruit formation…

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A typical stamen has three parts: filament, anther, and connective. The filament is the stalk, the anther is the fertile terminal part, and the connective is the tissue joining the two anther lobes.

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A dithecous anther has two lobes and four pollen sacs, so it is also called tetrasporangiate. It is the common type of anther in flowering plants. Hibiscus and Euphorbia have monothecous anthers inste…

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The wall of the microsporangium has four layers: epidermis, endothecium, middle layers, and tapetum. The tapetum is the innermost layer, dense in cytoplasm, and nourishes developing microspores.

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The tapetum nourishes sporogenous cells, microspore mother cells, and growing pollen grains. It secretes IAA, which is stored in pollen grains for early growth. It also helps form pollenkitt and tryph…

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Microsporogenesis is the formation of microspores from microspore mother cells by meiosis. Each microspore mother cell divides meiotically to form four haploid microspores. These microspores may remai…

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The callose layer binding the microspore tetrad is dissolved by callase, an enzyme secreted by the tapetum. After this, the microspores separate from one another and develop into pollen grains.