Anther or pollen culture in vitro gives rise to plants with haploid number of chromosomes. While naturally occurring haploids are rare as reported in Datura, Nicotiana, Coptis, and Arrhinium species, tissue culture–raised haploids are of great economic importance in plant-breeding programs and in mutation studies. By themselves sterile, they may be made to form homozygous diploids by colchicine treatment. Ever since Bourgin and Nitch (1967) raised the first mature haploid plants of Nicotiana, so far androgenic haploids have been raised in more than 200 species belonging to about 88 genera and 34 families. Haploids are used in crop improvement of wheat, barley, rye, maize, potato, tomato, sunflower, and peanut.