A review of the morphology of ohatsuki (stamen- or ovule-bearing) leaves, with relevance to physiological analyses of Ginkgo biloba

A Ginkgo biloba variant in which either stamens or ovules are generated on the edge of the leaf is known as “ohatsuki icho”. In this review, we highlight the morphological similarities among ohatsuki leaves, reproductive organs, and the leaves and seeds of fossil plants. Although ohatsuki phenotypes appear to be controlled by sex-related bud sports, their expression seems to be only possible in the river system, in the presence of seasonal winds, suggesting water-related control. We discuss a previous report suggesting that water conductance may contribute to the occurrence of ohatsuki malformations in ohatsuki shoots and leaves, although a physiological evaluation of water transpiration in ohatsuki leaves has yet to be conducted. The information presented in this review may provide insights into the evaluation of the above-mentioned hypothesis and may identify key factors related to sexual evolution in land plants.