## 2 Results
### PCA Analysis of Major VOCs and EOs Constituents
In total, 30 major compounds were identified in the samples obtained by using PDMS/DVB fiber and DVB/CAR/PDMS fiber for HS-SPME (Figures 4 and 5), while only 14 major compounds were identified in the EOs of the investigated _Iris_ taxa (Figure 6). The biplot constructed by the first two principal components showing the distribution of the investigated _Iris_ samples and major VOCs detected with PDMS/DVB fiber is presented in Figure 4. Principal component 1 (PC1) accounted for 39.31%, and principal component 2 (PC2) for 21.10% of the total variance in the data. Clear separation from the remaining samples was observed for _I. adriatica_, with camphor, (furan-2-yl)methanol, limonene, and 1,8-cineole being the distinctive VOCs, as well as for _I. pseudopallida_ D, with nonan-2-one, _cis-\(\alpha\)_-irone, and _cis-\(\gamma\)_-irone as the distinctive VOCs. The remaining samples of _I. pseudopallida_ and _I. illylrica_ were characterized by a range of components (e.g., dihydromycenol, perilla aldehyde, benzyl alcohol, acetic acid, ethanol, and butan-2,3-diol) and were not further separated from each other. The biplot constructed by the first two principal components showing the distribution of the investigated _Iris_ samples and major VOCs identified with DVB/CAR/PDMS fiber is presented in Figure 5. PC1 accounted for 36.55%, and PC2 for 24.87% of the total variance in the data. As with the former fiber, clear separation based on the presence of the same characteristic compounds was obtained for _I. pseudopallida_ D and _I. adriatica_, with furfural recognized as an additional distinguishing compound for the latter taxon. The remaining samples of _I. pseudopallida_ and _I. illylrica_ were grouped more closely together and were characterized primarily by acetic acid, \(\alpha\)-copaene, and nonanal. The biplot constructed by the first two principal components showing the distribution of investigated _Iris_ samples and major EOs constituents is presented in Figure 6. PC1 accounted for 49.50%, and PC2 for 23.27% of the total variance in the data. As in the samples obtained by HS-SPME, _I. adriatica_ was distinguished from other investigated taxa, based on the exclusive presence of two components that were not found in the extracts prepared by the former two methods, hexadecanoic acid and (Z,Z)-octadeca-9,12-dienoic acid. Moreover, _I. pseudopallida_ D was not only again characterized by _cis-\(\alpha\)_-irone but also by docosane. Unlike with the previous two methods, the PCA analysis of the samples VOCs obtained by HD resulted in additional separation of _I. pseudopallida_ B. The latter sample was characterized by several monoterpene alcohols, such as terpinen-4-ol, \(\alpha\)-terpineol, and myrtenol, together with \(\alpha\)-pinene (monoterpene hydrocarbon) and 2-phenylethanol (aromatic alcohol). The remaining samples of _I. pseudopallida_ and _I. illylrica_ were grouped together. Figure 4: Biplot obtained by principal component analysis of the VOC composition of the six investigated _Iris_ samples, based on their major components (average content \(\geq\)2.0% in at least one sample), detected using PDMS/DVB fiber; for compound abbreviation, cf. Supplementary Table S1. Figure 5: Biplot obtained by principal component analysis of the VOC composition of the six investigated _Iris_ samples, based on their major components (average content \(\geq\)2.0% in at least one sample), detected using DVB/CAR/PDMS fiber; for compound abbreviation, cf. Supplementary Table S1.