Micromorphologic study of the seed of the genus Trifolium, section Lotoidea, in Iran.

The characteristics of the seeds of 7 annual and perennial species of Trifolium, Lotoidea section, in Iran were investigated by means of Scanning Electron Microscopy (SEM) and a stereomicroscope. Contrary to Zohary's belief who maintained that the micromorphology of the Trifolium's seed played no role in taxonomy, the results revealed that such characteristics can play a determining role in differentiating such species and distinguishing them from one another. The results of the micromorphologic study of the seed confirmed the morphological results of the species of the Lotoidea section to a great extent, but was involved in the separation and differentiation of the two species of T. repens and T. nigrescens. In general, the characteristics of the species' seeds proved quite effective in determining their phenetic relationship. Among the characteristics studied in the present research, mention can be made of seed shape, hilum shape, seed sculpture and seed length and width (L/W ratio). The results demonstrated that the characteristics of seed length and hilum shape showed the greatest diversity in the species. The longest seed length was that of the species T. radicosum and the shortest that of T. repens. The spindle shape of the hilum was an exclusive characteristic of T. radicosum which distinguished it more than any other characteristic from all the other species of this section. The difference in hilum shape in the two species of T. repens and T. nigrescens was an important distinctive characteristic.