Structure of the Maize Ear as Indicated in Zea-euchlaena Hybrids

In attempting to trace the origin of maize (Zea mays L.) the center of interest is the evolution of the peculiar form of inflorescence, especially the pistillate inflorescence, or ear. Since Euchlaena (Etwhlaena mexicana Schrad.) or teosinte, the nearest known relative of maize, has a very different type of pistillate inflorescence, it may be instructive to compare the two genera and trace the successive changes that would be required in passing from the Euchlaena form of pistillate inflorescence to the maize ear. Euchlaena and maize cross freely, resulting in intermediate hybrids which in subsequent generations grade back to the parental forms (PL 16). It is therefore possible to present a complete series of intermediates, graduated to any desired degree of minuteness. It should be kept in mind that although we may be able to arrange a continuous series of forms ranging from Euchlaena to maize, these forms may not represent the course of evolution. A study of these intermediate hybrids may be expected, however, to throw light on the morphology of the ear and to explain its evolution, at least in a mechanical sense.