Reduced genetic variability within the cultivated gene pools of crop species is a phenomenon of contemporary agri cultural systems. In extreme circumstances, this reduction can suspend progress from selection or precipitate catastrophies such as the Irish potato famine (Salaman, 1949). Con sequently, the introgression of germplasm from exotic, wild, or weedy relatives is an integral part of many plant breeding programs (Harlan, 1976; Hawkes, 1977). In the broadest sense, introgressive hybridization is the incorporation of germplasm from one isolated population into another of the same or a related species (Heiser, 1973). It is believed to play an evolutionary role, and introgression between sympatric domesticated plants and their wild relatives is common (Stebbins, 1959; Anderson, 1961; Heiser, 1973). Maize Cultivated maize (Zea mays L,) is the product of repeated racial hybridization within the species and recurrent intro gression from teosinte (Z. mexicana) and Tripsacum (Mangelsdorf, 1961). Anderson and Brown (1952) considered the hybrids between the Southern Dent and Northern Flint maizes diverse enough to be interspecific and suggested a reexamination of these races to create maximum heterozygosity.