Background and Aims Aerenchyma formation is thought to be one of the important morphological adaptations to
hypoxic stress. Although sponge gourd is an annual vegetable upland crop, in response to flooding the hypocotyl and
newly formed adventitious roots create aerenchyma that is neither schizogenous nor lysigenous, but is produced by
radial elongation of cortical cells. The aim of this study is to characterize the morphological changes in flooded
tissues and the pattern of cortical aerenchyma formation, and to analyse the relative amount of aerenchyma formed.