Pod corn

Abstract: Publisher Summary Maize is a grass, though in some respects a most unusual one, as the herbalists and early botanists clearly recognized. Within the grass family (Gramineae), maize is assigned to the tribe Maydeae, a tribe comprising eight genera, five of which are Oriental and three American. This chapter discusses the origin of maize and reviews the cytogenetic studies that led to the tripartite hypotheses. Evidence derived from the studies based on genetics, cytology, morphology, archaeology, ethnology, and history led to the development of a tripartite hypothesis, that cultivated that maize originated from a wild form of pod corn that was once, and perhaps still is, indigenous to the lowlands of South America. Teosinte, the closest relative of maize, is a recent product of the natural hybridization of Zea and Tripsacum that occurred after cultivated maize had been introduced by man into Central America. The new types of maize originating directly or indirectly from this cross and exhibiting admixture with Tripsacum comprise the majority of Central and North American varieties.

Abstract: The hypothesis which holds that cultivated maize has been derived from a wild form of pod corn at one time indigenous to the lowlands of South America is at once the oldest and among the youngest of the various propositions which have been developed to explain the origin of this unique New World cereal. More than a century ago the French naturalist, Saint-Hilaire (1829), described as a new variety Zea Mass var. tunicata, a peculiar type of maize sent to him from Brazil in which the grains were covered by the glumes. He concluded that this was the natural state of maize and that South America (Paraguay) was its native home. Virtually all students of maize since Saint-Hilaire have given serious attention to pod corn, have recognized its primitive characteristics, and have either accepted it as the ancestral form, or, for a variety of reasons, have dismissed it from this role. Their viewpoints and conclusions are reviewed and discussed in detail by Mangelsdorf and Reeves (1939). Here it will suffice to set forth the principal reasons given by various students who dismissed pod corn as the ancestral form of maize: (1) it does not breed true; (2) it apparently arises spontaneously in cultures of normal maize; (3) it is frequently monstrous; (4) it differs from normal maize primarily by a single gene; (5) the hypothesis that teosinte is the ancestral form of maize is a more plausible one. Of the five reasons given for rejecting the pod-corn hypothesis the last is particularly important, for, once the close relationship of maize and teosinte was widely recognized, the pod-corn hypothesis was relegated to a distinctly secondary role. Only recently has it again been brought into prominence by Mangelsdorf and Reeves (1939) who, on the basis of experimental evidence, concluded that teosinte, far from being the progenitor of maize, is instead the progeny of the hybridization of maize and Tripsacum. Having dismissed teosinte as the ancestral form of maize, they turned to the earlier pod-corn hypothesis as the only plausible alternative. The present paper is concerned not with the entire problem of the origin of maize but primarily with the pod-corn hypothesis, and particularly with a mass of new experimental evidence and new observations accumulated during the past ten years which have a bearing upon the problem of the role of pod corn in the origin and evolution of maize. Data previously published are included only to the extent that they are needed in presenting a complete picture; and the extensive literature on pod corn is reviewed only to the extent of providing an adequate background for the present discussion. For more detailed reviews of the literature on pod corn and for earlier data the reader is referred to Sturtevant (1899), Weatherwax (1935), and Mangelsdorf and Reeves (1939).

Abstract: New evidence concerning the origin of maize — a question which has puzzled botanists for more than a century — has made it possible to reach several rather definite conclusions: (1) Maize is undoubtedly an American plant. (2) Maize undoubtedly had at least one center of origin in Middle America. (3) The ancestor of maize is maize. (4) The ancestor of maize is a form of pod corn, hut perhaps not the extreme type of pod corn known today. The ancestor was certainly a popcorn. (5) Sometime in its history maize hybridized with Tripsacum or teosinte or both to produce radically new types which comprise the majority of modern maize varieties of North America. The evidence on which these rather sweeping conclusions rest comes from three fields —botany, archaeology, and genetics. Substantially conclusive evidence of the American origin of maize was obtained from fossil pollen grains discovered at a depth of more than 200 feet below Mexico City.