## 3 Results and Discussion
### Results of Poted Experiments on Remediation Plants
\begin{table}
\begin{tabular}{c c c} \hline \hline \multirow{2}{*}{**Plants**} & **Average Root Length** & **Average Plant Height** & **Moisture Content** \\  & **(cm)** & **(cm)** & **(\%)** \\ \hline _Cynodon dactylon_ & 9.1 \(\pm\) 0.1 c & 9.6 \(\pm\) 0.5 b & 68.1 \(\pm\) 0.8 c \\ _Bidens pilosa_ & 9.7 \(\pm\) 0.5 b & 8.5 \(\pm\) 0.7 c & 71.5 \(\pm\) 0.6 b \\ _Boehmeria nivea_ & 11.7 \(\pm\) 0.4 a & 12.7 \(\pm\) 0.4 a & 75.5 \(\pm\) 0.8 a \\ \hline \hline \end{tabular} The table presented the one-way ANOVA results for plant height, root length, and water content for three plant species. Each set of data had a sample size of \(n\) = 3. The letters “a”, “b”, and “c” denote significant differences among the means, with the same letter indicating no significant difference. The significance level is indicated by \(p\), with \(p\) < 0.05 denoting a significant difference.  
\end{table} 
Table 2: The growth parameters of plants (\(p\) < 0.05). \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Heavy**} & \multicolumn{3}{c}{**Cynodon dactylon**} & \multicolumn{3}{c}{_Bidens pilosa_} & \multicolumn{3}{c}{_Boehmeria nivea_} \\
**Metal** & **BG** & **AG** & **BCF** & **TF** & **BG** & **AG** & **BCF** & **TF** & **BG** & **AG** & **BCF** & **TF** \\ \hline As & 73.20 & 16.80 & 0.43 & 0.23 & 63.35 & 15.95 & 0.33 & 0.25 & 7.40 & 4.50 & 0.07 & 0.61 \\ Cd & 0.09 & 0.03 & 0.13 & 0.33 & 0.15 & 0.25 & 0.62 & 1.67 & 0.07 & 0.01 & 0.08 & 0.14 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Belowground (BG)/aboveground (AG), As and Cd content (mg/kg), bioconcentration factor (BCF), and translocation factor (TF) of plants. Bidens pilosa_ had the best overall remediation effect among the three plants. Additionally, only the translocation factor of _Bidens pilosa_ for Cd was greater than 1, demonstrating its outstanding ability of Cd translocation; as a result, _Bidens pilosa_ was found to be the best candidate for subsequent research. For the pollution in contaminated soil, despite the fact that the total contents of As and Cd are important indicators, their biological effects should given more attention; these were mainly determined by the bioavailability of As and Cd. As observed in Table 4, to varying degrees, all three plants succeeded in reducing the bioavailability of As and Cd, and the reduction effectiveness ranked as _Bidens pilosa > Cynodon dactylolm > Boehmeria nivea_. _Bidens pilosa_ had the highest reduction rate in the bioavailability of As and Cd. Therefore, _Bidens pilosa_ was chosen as the remediation plant for further research. Understanding the physiological morphology and seed dispersal methods of _Bidens pilosa_ contributed to our understanding of the application's effectiveness in combined remediation. Therefore, a corresponding study was conducted. The seeds of _Bidens pilosa_ were collected, air-dried, and stored at room temperature. Fully developed seeds were selected for observing their morphological characteristics, as shown in Figure 3.  
As shown in Figure 3A, _Bidens pilosa_ exhibited robust growth in the wild environment, with significant plant height and abundant biomass, making it highly suitable for greening the soil in the contaminated area. Additionally, this herbaceous plant could increase the content of organics, quick-acting nitrogen, and quick-acting potassium in the soil, thereby  
Figure 3: The physiological characteristics of _Bidens pilosa_ (**(A)**: Growth status of _Bidens pilosula_ in wild environments; **(B)**: Reproductive organs of _Bidens pilosula_; **(C)**: Physical picture of the seeds of _Bidens pilosula_; **(D)**: The top of _Bidens pilosula_ seed was prickly and hooked). enhancing the fertility of the soil in the contaminated area [52; 53], creating favorable conditions for crop cultivation after remediation. As depicted in Figure 3B, _Bidens pilosa_ had well-developed breeding organs, a large seed-carrying capacity, and well-formed seed morphology, showing the high development of its breeding organs.