Comparative seed morphology of Trifolium L. Species (Fabaceae)

Background and Purpose: Seed morphological characteristics proved to be useful taxonomic features, helpful in identification of large number of species and genera. Seed characters, such as shape, size and seed-coat surface, have low phenotypic plasticity and are less affected by environmental conditions. The purpose of this study was to describe and compare external seed morphological characteristics of 38 Trifolium species, and to evaluate their possible use for taxonomic considerations. Material and Methods: The seedswere gained from genebanks and seed collections and examined using light and scanning electron microscopy (SEM). Obtained data were statistically processed using analysis of variance, Principal Component Analysis and Multiple Correspondence Analysis. Results and Conclusions: The results showed that seeds were laterally compressed and bilobed and showed morphological variations in size, shape, color, seed coat ornamentation and morphology of the radicle lobe. Examined characters did not provide considerable information that could be used to distinguish subgenera or sections of this genus, because seed characteristics did not support the subgeneric classification. A unique seed coat morphology and combination of other seed characteristics permitted easy identification of some of the examined species, like T. subterraneum, T. alexandrinum, T. angulatum and T. vesiculosum