Excess water can induce flooding stress resulting in yield loss of crops, even in wetland plants such as rice. However, traits from species of wild Oryza have already been used to improve tolerance to abiotic stress in cultivated rice. This study aimed to establish root responses to sudden soil flooding among 8 wild relatives of rice with different habitat preferences benchmarked against 3 genotypes of O. sativa. Plants were raised in hydroponics, mimicking drained or flooded soils, to assess the plasticity of adventitious roots. Traits included were apparent permeance (PA) to O2 of the outer part of the roots, radial water loss (RWL), tissue porosity, apoplastic barriers in the exodermis and root anatomical traits. These were analysed using a plasticity index and hierarchical clustering based on principal components analysis. For example, O. brachyantha, a wetland species, possessed very low tissue porosity compared to other wetland species, whereas dryland species O. latifolia and O. granulata exhibited significantly lower plasticity compared to wetland species and clustered in their own group. Most species clustered according to growing conditions based on PA, RWL, root porosity and key anatomical traits, indicating strong anatomical and physiological responses to sudden soil flooding.