The development of large rhizomes in bermudagrass ecotypes significantly contributes to drought tolerance and rapid recovery from severe drought. This study investigated the relationship between rhizome growth in bermudagrass (Cynodon spp.) ecotypes and the environmental conditions of their original collection sites. A total of 142 naturalised bermudagrass ecotypes were collected from the Australian continent, where the environments at their origins show minimal differences in average temperature but significant variation in rainfall. A 14-week pot experiment was carried out over the summer to assess rhizome dry weight (RhiDW), and the morphological characteristics of the shoots. There was no difference in rhizome dry weight (RhiDW) among ecotypes sourced from arid and non-arid areas, with the ecotype exhibiting the highest RhiDW originating from an arid region. Substantial rhizome development was linked to a higher annual rainfall in their native environments (r = 0.22), and this trend was enhanced for the ecotypes collected from arid zones (r = 0.41). Rhizome growth was positively associated with the belowground-to-aboveground biomass ratio (BAR, r = 0.61) and leaf width (r = 0.55), while BAR displayed a negative correlation with internode length (r = -0.44). These results imply that the drier environment of the native habitats did not drive the evolution of bermudagrass toward larger rhizome development. Broader leaves enhance rhizome growth and may serve as a key characteristic for breeding bermudagrass varieties with improved drought tolerance.