Curvature Analysis of Seed Silhouettes in the Euphorbiaceae

The Euphorbiaceae is a large, diverse, and cosmopolitan family of monoecious or dioecious trees, shrubs, herbs, and lianas. Their name comes from Euphorbia, one of the largest genera in the Angiosperms, with close to 2000 species and a complex taxonomy. Many of their members have an economic interest in multiple applications, including pharmaceutical, nutritional, and others. The seeds of the Euphorbiaceae develop in schizocarps and have a diversity of shapes that have proven useful for species identification and classification. Nevertheless, analytical quantitative methods can be the subject of further development for the application of seed morphology in the taxonomy of this family. With this objective, measurements of size (area, perimeter, length, and width) and shape (circularity, aspect ratio, roundness, and solidity) in seed images of 230 species representative of the main taxonomic groups of Euphorbiaceae are presented, and curvature analysis is applied to 19 species. Seed images corresponding to many species of this family present a tetragonal pattern with a curvature peak in the apical pole and three in the basal pole. The results of the curvature analysis are discussed in relation to other morphological properties, revealing new aspects of seed morphology of taxonomic application.