Measurements of cotton boll segments from caves near Mitla, Oaxaca, Mexico, datable between 700 and 1300 A.D., indicate that the archaeological material is more closely related to the modern racespunctatum andlatifolium ofG. hirsutum than it is to other races. This is supported by the shape of the bolls and, particularly, by the high percentage of tufted seeds found in the archaeological cotton.
That the material isG. hirsutum has now been confirmed by examination of an archaeological peduncle which clearly shows the fringe of hairs above the true floral nectary, virtually a hallmark of the species. The external extra-floral nectaries completely eliminate the possibility that this could be an Asiatic cultivated cotton.
All of the Mexican archaeological cotton known so far is completely domesticated. We have no evidence as to where cotton originated as a cultigen. It was introduced into the Tehuacán and Oaxaca Valleys as a cultivated plant.