Soybean cultivars which occupy a majority of the U.S. acreage trace to only a few maternal parents. According to a recent report (1972) by the National Academy of Sciences, the maternal ancestors and their combined frequency of occurrence in the parentage among Northern and Southern varieties are: \u27Mandarin\u27 51 %, \u27Illini\u27 23%, \u27Tokyo\u27 11 %, \u27Dunfield\u27 8%, \u27Mukden\u27 4%, and \u27Roanoke\u27 4%. Four of these parents are introductions from Manchuria, one from Japan, and one is of unknown origin
