ABSTRACT
Apomixis is derived from sexual reproduction. Most angiosperms reproduce sexually, either exclusively, or combined with one or more kinds of asexual reproduction. Sexual reproduction promotes genetic variation; but it also seems to involve expenditure of time and effort. Asexual reproduction involves the purely vegetative reproduction through dividing somatic cells, for instance by runners, rhizomes, and bulbils. In most cases, adventitious embryony occurs in the presence of normal sexual reproduction. The chapter provides descriptions of embryology, cytology, and other data concerning various kinds of apomixis. The nomenclature is complex and sometimes even confusing; alternative terms and classifications are discussed. The varying use, or misuse, of apomictic terminology seems rather to be an obstacle for the student of papers on apomixis. Crane proposes that all apomeiotic mechanisms can be grouped into the following four categories: altered meiosis, impedispory, quasispory, and quasidikaryony.
