Homologies of the Ear and Tassel in Zea Mays

The exact correspondence between the variation of the male and female inflorescence of Zea Mays is a problem which has attracted a number of minds and has produced several theories, none of which completely satisfied the existing data. The morphological facts have been assembled by Weatherwax ('23, '35), and he, Collins ('19) and Kempton ('19) have reviewed the pertinent literature. After surveying all the existing evidence Collins' final conclusion was that, though he had used the hypothesis of a shortened and twisted central spike to explain the results in crosses between Zea and Euchlaena, "'facts of other kinds are more easily interpreted by the theories -of fasciation and reduction of branches . . . . There are also facts that do not seem to accord with any of the theories yet proposed. Until the apparently contradictory evidence can be reconciled, it seems best to keep the several possibilities in mind and await additional evidence before attempting a complete interpretation." Though the facts reported below shed further light on the problem, Collins' words of caution are still in order and the complete solution, while perhaps not far distant, is still to be awaited. Though he disagreed rather completely with Collins on other points, Weatherwax's final conclusions ('23) concerning the ear were very similar. "The last word has not yet been said on the evolution of the ear of corn, and it cannot be said until further researches have corrected, amplified, and evaluated the data now at hand, and woven the results into a harmonious theory." [loc. cit. pp. 112-113]. Earlier workers were interested in the problem of ear and tassel relationships chiefly from theoretical considerations. With the development of large-scale scientific maize breeding in the U. S. cornbelt, itis now a problem of considerable economic importance as well. If a corn breeder could size up the potentialities of the ear, merely by examining the tassel, he could take many short cuts, both in the creation of new inbred lines and in maintaining their desirable characters.