Flowering plants have a reproductive cycle in which a diploid sporophytic phase alternates with a haploid gametophytic phase. The plant represents the sporophyte, and the gametophytes are microscopic. As illustrated in the double fertilization entry, the male gametophyte is the pollen grain and the female gametophyte is the embryo sac. However, parthenogenetic development of unfertilized eggs can occur, but it is very rare. Haploid sporocytes were first reported in Datura stramonium (q.v.). The frequency of haploid plants can be greatly increased using anther culture (q.v.). Homozygous diploid plants can then be generated by treatment with colchicine (q.v.). See Chronology, 1922, Blakeslee et al.; alternation of generations.
Subjects: Genetics and Genomics.