## 3 Results
Soil physiochemical characteristics and diversity indices correlated with the HM contaminated sites are presented in Table 2. The soil texture shows a sandy texture with higher percentage of silt and clay. The pH for soil samples was slightly acidic to neutral ranging from 6.60 \(\pm\) 0.18 to 6.925 \(\pm\) 0.110. Organic matter content was quite low (roadside = 0.710 \(\pm\) 0.12; urban = 1.188 \(\pm\) 0.19; rural = 0.719 \(\pm\) 0.149) in all sites tested as the plant prefers to grow in desert type soils having high sand contents. The sample soils of roadside sites had a higher lime concentration (8.96 \(\pm\) 0.77), followed by rural and urban areas. The lowest mean value of total bioavailable nitrogen was found in rural areas (0.060 \(\pm\) 0.02), while the highest mean value of total nitrogen was identified in urban areas (0.142 \(\pm\) 0.03). The results demonstrate that the nitrogen content in all habitats is higher, except rural areas, which has a low nitrogen concentration. Phosphorous content (mg kg\({}^{-1}\)) of soil in all the habitats was low. Potassium content was 97.72 \(\pm\) 11.89 (mg kg\({}^{-1}\)) in the soil of rural areas, which is higher than the soil of all other habitats. Table 2 shows diversity indices, origin, and sampling sites of _C. procera_ reported from 15 different sites of Khyber Pakhtunkhwa, Pakistan. The plant was found in patches with lower species diversity and evenness. _Carthamus lamatus, Cynodon dactylon, Xanthium stratumium_, and _Silbyum marianum_ were the dominant species of the plant communities in the investigated areas. The Shannon diversity index was found to be highest for roadsides (2.13 \(\pm\) 0.06). The lowest Shannon diversity index was found for rural areas (1.38 \(\pm\) 0.00). Species diversity (H\({}^{\prime}\)), richness (Rs), and evenness (Eh) indices showed significant differences between the three habitats. Diversity within communities decreased with the increase in metal concentration in the soil, which is directly linked with species richness and Shannon diversity index. The diversity indices follow the order of roadside > urban areas > rural areas as presented in Table 2.  
The HMs content of soil and _C. procera_ are presented in Table 3, which shows the roadside areas having the highest concentrations of HMs followed by urban site compared to rural sites. The Zn and Pb concentrations in soil were within the range of permissible levels. Figure 2: Cluster dendrogram establishing three major groups of contaminated sites based on soil pollution index (SPI). Phytoremediation potential of plants for Pb, Zn, Cu, and Cd was indicated by a bioaccumulation factor (BAF) from soil to plant, and translocation factor (TF) from soil to plant organs presented in Tables 4 and 5. The BAF in roadside areas was higher in root than the whole plant indicating that metal is retained in the root compared to its aerial parts. Simultaneously, the reverse is true for urban and control areas, which may be due to low metal concentration allowing for plant growth and favouring the transfer of metal to aerial portions, thus increasing the BAF. The BAF value for the root of plants growing on the roadside sites was more than 1, indicating its hyper accumulation ability and can be used efficiently in phytoremediation operations particularly for Zn and Cu. The BAF for Pb was found to be more than 1 in roadside areas for root, which suggested that _C. procera_ can absorb and accumulate Pb (Table 4). The translocation factor (TF) is an important indicator for the transportation of metal in living tissues, from root to stem (R-S), stem to leaves (S-L), and from leaves to flowers (L-F) of a plant body. Table 5 presents the TF of Zn, Pb, Cu, and Cd in different habitats. Translocation factors for roadside areas and urban areas show a similar pattern in all the studied sites. The TF value was less than 1.00 for R-S, and greater than 1.00 from S-L. Pb TF values for R-S and S-L were found to be higher than 1 in roadside areas.