(orange, red and purple) was submitted to the principal component analysis (PCA) and hierarchical cluster analysis (HCA) with autoscaling pretreatment [27,29]. Since PCA is a well-known chemometrics technique of multivariate analysis, which turns it easier to visualize grouping tendencies, using the whole information contained in a large number of variables, this tool was employed to intensify grouping tendencies of different biotypes of E. uniflora leaves, based on their VOCs
profiles. HCA is a statistical tool to pool samples based on similarities,by measuring distances between all possible pairs of samples in dimensional space. The Pirouette 3.11 (Infometrix, Woodinville, WA) was employed for chemometrics package PCA and Origin 8.1 (OriginLabCorp.) was used to generate the graphics 3D PCA score and loading as
a function of the eigenvalues and eigenvectors calculated using the Pirouette. Heatmap and dendrogram of metabolites identified were constructed using the MetaboAnalyst 3.0 package.