Introduction and Milestones in Plant Embryology

Reproduction is one of the essential features of every living thing, and in plants it does far more than secure the species' own survival. Because almost every other organism on Earth depends, directly or indirectly, on plants, plant reproduction underwrites the continuity of life more broadly, and the variation it introduces into offspring is also a significant driver of evolution. Reproduction in plants, as already outlined in Unit I of Class XI, falls into two broad categories that this unit takes up in turn: asexual reproduction, which perpetuates a species without any involvement of gametes, and sexual reproduction, which depends on the production and fusion of male and female gametes. The chapter that follows works through both routes in detail, from the vegetative and other asexual methods flowering plants use, through the structures and events of sexual reproduction, to related phenomena such as apomixis, polyembryony and parthenocarpy.