## 2 Results
### Phenotypic Space of VOCs in Three Flowering Stages  
A total of 37 VOCs were detected by HS-SPME-GC-MS analysis. Among them, 31 VOCs (83.78%) were identified. Over the three stages of flowering, 29 VOCs were emitted during the full-blooming period (T2), 17 were emitted during the over-blooming period (T3), and 11 during the pre-blooming period (T1). The main chemical categories of flower scent in the three flowering stages were aliphatic alcohols, aliphatic alkanes, benzenoids, monoterepenes, and irregular terpen. Flowers released mostly monoterepenes (11), followed by aliphatic alcohols (6) and aliphatic alkanes/aldehydes (3). Among the 31 identified compounds, eight aliphatic compounds were present in all three flowering stages, albeit in markedly different proportions (Figure 1, Table S1). Aldehydes accounted for 89.95% of the total amount of aroma substances and were the most abundant aroma components at the pre-blooming stage (T1). They also accounted \begin{table}
\begin{tabular}{c c c c c c c} \hline
**Code** & **Fibers (A)** & \begin{tabular}{c} **Adsorption** \\ **Temperature (B)** \\ \end{tabular} & \begin{tabular}{c} **Adsorption** \\ **Time (C)** \\ \end{tabular} & \begin{tabular}{c} **Sample Weight** \\ **(D)** \\ \end{tabular} & \
\begin{tabular}{c} **Desorption** \\ **Time (E)** \\ \end{tabular} &
\begin{tabular}{c} **Peak Area** \\ \end{tabular} \\ \hline
1 & 1 & 1 & 1 & 1 & 1 & 3.97 \(\times\) 10\({}^{6}\) \\
2 & 1 & 2 & 2 & 2 & 2 & 6.70 \(\times\) 10\({}^{6}\) \\
3 & 1 & 3 & 3 & 3 & 3 & 9.70 \(\times\) 10\({}^{6}\) \\
4 & 1 & 4 & 4 & 4 & 4 & 1.08 \(\times\) 10\({}^{7}\) \\
5 & 2 & 1 & 2 & 3 & 4 & 4.96 \(\times\) 10\({}^{5}\) \\
6 & 2 & 2 & 1 & 4 & 3 & 1.04 \(\times\) 10\({}^{6}\) \\
7 & 2 & 3 & 4 & 1 & 2 & 1.74 \(\times\) 10\({}^{6}\) \\
8 & 2 & 4 & 3 & 2 & 1 & 7.05 \(\times\) 10\({}^{5}\) \\
9 & 3 & 1 & 3 & 4 & 2 & 3.95 \(\times\) 10\({}^{6}\) \\
10 & 3 & 2 & 4 & 3 & 1 & 6.06 \(\times\) 10\({}^{6}\) \\
11 & 3 & 3 & 1 & 2 & 4 & 1.05 \(\times\) 10\({}^{7}\) \\
12 & 3 & 4 & 2 & 1 & 3 & 7.80 \(\times\) 10\({}^{6}\) \\
13 & 4 & 1 & 4 & 2 & 3 & 2.35 \(\times\) 10\({}^{7}\) \\
14 & 4 & 2 & 3 & 1 & 4 & 1.77 \(\times\) 10\({}^{7}\) \\
15 & 4 & 3 & 2 & 4 & 1 & 9.51 \(\times\) 10\({}^{7}\) \\
16 & 4 & 4 & 1 & 3 & 2 & 6.19 \(\times\) 10\({}^{7}\) \\ \(\overline{\text{k}}_{1}\) & \(7.80\times\) 10\({}^{6}\) & \(7.99\times\) 10\({}^{6}\) & \(1.94\times\) 10\({}^{7}\) & \(7.81\times\) 10\({}^{6}\) & \(2.65\times\) 10\({}^{7}\) & \\ \(\overline{\text{k}}_{2}\) & \(9.94\times\) 10\({}^{5}\) & \(7.88\times\) 10\({}^{6}\) & \(2.75\times\) 10\({}^{7}\) & \(1.04\times\) 10\({}^{7}\) & \(1.86\times\) 10\({}^{7}\) & \\ \(\overline{\text{k}}_{3}\) & \(7.08\times\) 10\({}^{6}\) & \(2.93\times\) 10\({}^{7}\) & \(8.02\times\) 10\({}^{6}\) & \(1.95\times\) 10\({}^{7}\) & \(1.05\times\) 10\({}^{7}\) & \\ \(\overline{\text{k}}_{4}\) & \(4.96\times\) 10\({}^{7}\) & \(2.03\times\) 10\({}^{7}\) & \(4.66\times\) 10\({}^{6}\) & \(2.77\times\) 10\({}^{7}\) & \(9.89\times\) 10\({}^{6}\) & \\ R & \(4.86\times\) 10\({}^{7}\) & \(2.14\times\) 10\({}^{7}\) & \(2.29\times\) 10\({}^{7}\) & \(1.99\times\) 10\({}^{7}\) & \(1.66\times\) 10\({}^{7}\) & \\ \hline Optimization level & & & & & & \\ \hline \end{tabular}
\begin{tabular}{c} A\({}_{4}\)B\({}_{3}\)C\({}_{2}\)D\({}_{4}\)E\({}_{1}\) \\ \end{tabular}
\end{table} 
Table 2: Optimized results of HS-SPME parameters by an L\({}_{16}\) (4\({}^{5}\)) orthogonal test. Figure 1: Venn analysis of volatile organic compounds (VOCS) of _L. caudata_ at three flowering stages. T1: pre-blooming stage; T2: full-blooming stage; T3: over-blooming stage. for 34.14% in the over-blooming stage (T3), but made up only 6.02% of the total aroma content during full-blooming stage (T2). Alcohols were one of the main aroma components during the flowering stage of _L. caudata_. Among them, 2-nonanol (20.86%) had the highest content in the full-blooming period and the content of 1-hexanol (32.23%) was the highest at the over-blooming stage.