Elliptic Fourier analysis of leaf shape of Callicarpa pedunculata and Callicarpa rubella (Lamiaceae)

Leaves play an important role in species discrimination. An elliptic Fourier analysis (EFA) based morphometric technique was used to assess divergence between the poorly differentiated species, Callicarpa pedunculata and C. rubella. Using leaf specimen images from herbarium collections, principal components (PCs) were extracted from the Fourier coefficients and used to describe leaf outline and leaf shape descriptors: circularity, aspect ratio, and solidity. The results indicate that symmetric (54%) and asymmetric (35%) components of the leaves of C. pedunculata and C. rubella are sources of shape variation, as shown in the width and leaf tips among the samples. MANOVA revealed significant interspecific differences (P = 0.03) between C. pedunculata and C. rubella. The jack-knife cross-validation showed 71% of correctly classified species both in C. pedunculata and C. rubella. Furthermore, the results of this study were able to reveal significant leaf shape descriptors like aspect ratio, circularity, and solidity as important diagnostic characters in discriminating C. pedunculata and C. rubella. Thus, in conclusion, leaf serrations, leaf size, and leaf lobes are important characteristics in discriminating between C. pedunculata and C. rubella.