This book discusses plant viruses, bacteria (and bacteria-like organisms), cyanophycota and some eukaryotic algae and fungi which have highly specialized reproductive structures and mode of reproduction. The reproduction in these groups is largely based on their physiology, biochemistry and genetics. The archegoniates (bryophytes, pteridophytes and gymnosperms) have several common features, as have the seed plants (gymnosperms and angiosperms). Reproductive biology is discussed and abundant illustrations are provided in various chapters. Each chapter has been prepared by a specialist to meet the course-work of undergraduate and postgraduate students. In several chapters, the authors have discussed the future trends in the twenty-first century. For a better understanding, a glossary is provided in many chapters.