THE SYSTEMATIC SIGNIFICANCE OF SEED MICRO-MORPHOLOGY IN STELLARIA L. (CARYOPHYLLACEAE) AND ITS CLOSEST RELATIVES IN IRAN

In this study, seed micro-morphology of eight species of Stellaria and two of its closest relatives were examined by scanning electron microscope. High variation was found in seed coat micromorphology and four distinc cell patterns were observed. Shape of testa cells is defined as elongated polygonal, broad polygonal, interlaced polygonal and irregular polygonal. The variation in ornamentation of testa cells as well as their size and shape may provide useful diagnostic characters for separating taxa at the generic and specific level. Seeds of the Myosoton aquaticum are reniform with rounded polygonal cells that are convex on the surface, having papillae on outer periclinal walls and V-shape anticlinal walls. This cell pattern is very similar to Stellaria media and S. pallida. Seeds shape of Mesostemma are cubical-spherical and the surface of seeds are arranged in irregular polygonal cell, irregular zip-shape margin and corrugated in periclinal wall. These are very different with exomorphology of the seeds of the Stellaria species. Seed micro-morphological data suggest that Myosoton aquaticum belongs to Stellaria and is better to be included as a synonym of it, but this data provides some support at least for the separation of Mesostemma kotschyanum from Stellaria.