This paper aims to investigate the root characteristics of three woody species (Pinus brutia, Quercus coccifera and Spartium junceum) planted on steep soil-denuded slopes, surfaced after ring-road excavation. The planted slopes were almost vertical, south faced and adding no soil. Fifteen plants per species were manually extracted for root system analysis and testing. The findings showed that the survivorship was different among the investigated species with S. junceum plants to survive better. The studied species follow different patterns of root development which in all cases were strongly affected by the adverse site conditions. The taproots, in all cases, got tapered and shortened rapidly in the length of the digging hole’s depth, while the density of lateral roots increased, especially in the case of S. junceum. Root tensile breaking force differed among the species and it was found to correlate
with root diameter. The resistance force from the cracks resulted in a deformation of embedded roots (flat-shaped roots instead of circular). The specific adaptation, which enables the plants to persist in such adverse environments, seems to be the number of embedded roots which were constant among the three studied species. However, based on the overall species performance, S. junceum appeared to be the best adaptable for eco-engineering purposes.