Geometric morphometrics of leaves of Cynanchum acutum L. (Apocynaceae) from Egypt

Abstract

This study aimed to revise Cynanchum acutum in Egypt and their relative subspecies that belonging to Section Cynanchum (Old World) and comparing it with an American group of genera Cynanchum laeve subgen. (Sect.) Mellichampia (New World) by using classical taxonomy and Modern geometric morphometric methods (GMMs). The description of 85 specimens depending on 36 quantitative traits was measured on each of the leaves using ImageJ Tool software. Data of leaf descriptors was further processed by using R program. Heatmap appeared to be more fluctuating between two color levels indicated to the similarity and dissimilarity between taxa and population, likewise, a PCA biplot showed a total variation 37.7% at first axis and 8.9% at the second. Significant variation in taxa and populations estimated using ANOVA and MANOVA. Canonical variate analysis showed a significant difference between taxa (P=0.001***), with a total variation of 67% between three taxa. The total variation Checked between two taxa by using discriminant analysis, C. acutum subsp. acutum and C. acutum subsp. sibiricum calculated 77% variation, while as the total variation between then between C. acutum subsp. acutum and C. laeve show 86% of the variation and significant value (P=0.002**). The study elucidated the situation of Cynanchum acutum in Egypt and confirmed the presence of two subspecies viz.: subsp. acutum and subsp. sibiricum