The biochemical and physical duet of the mother and the fetus in the formation of the placenta is one of the most carefully orchestrated phenomena in fetal development. It represents the cooperation of two distinct individuals to form a single structure that protects one and enables the genes of the other to live on.
This cycle is known as alternation of generations. The spores of seed plants, however, are produced internally and the megaspores, formed within the ovules and the microspores are involved in the formation of more complex structures that form the dispersal units, the seeds and pollen grains.
Plant Reproductive Structures. Plant sexual reproduction relies on stamens, which are the male parts, and pistils, which are the female parts. Stamens contribute the male genetic material in the form of pollen, which is produced from anthers that are on the terminal ends of stalks called filaments.tamens contribute the male genetic material in the form of pollen, which is produced from anthers that are on the terminal ends of stalks called filaments.