Abstract
Development of the female spikelets induced by gibberellin in the tassel was investigated. Female spikelets induced by gibberellin developed in the same manner as normal male spikelets, until carpel differentiation stage. Pistil primordium of the normal male floret aborted after carpel initiation, and the differentiation of the procambium in it was not observed. The female florets induced by gibberellin differentiated procambium in the pistil primordium and the pistil continued development without abortion. Stamens of the female florets aborted, though procambium connected with that of the spikelet differentiated in it. Development of a pistil in an upper floret appeared to inhibit the development of the stamens and a lower floret. From these observations it was deduced that procambium differentiation in a pistil primordium of the upper floret was important as to sex expression of the spikelet in Zea mays, and gibberellin might induce female spikelets in the tassel, through the promotion of the procambium differentiation in a pistil primordium which under normal conditions aborted
