Seed micromorphology and its implication in subgeneric classification of Silene (Caryophyllaceae, Sileneae)

- Seed morphology of 42 species of Silene representing 22 sections is performed.
- Silene sects. Conoimorphae, Melandriformes and Sclerocalycinae have consistent seed types.
- The extensive variation observed affords recognition of some taxa in taxonomic complexes.
- The echinate testa in Agrostemma githago, is lost in S. delicatula and reappeared in few other taxa.

Silene with more than 700 species worldwide is taxonomically complex and problematic. The previously proposed relationships among species as reflected in the subgeneric classification of the genus were mainly based on overall similarities in morphological traits and were rejected by the majority of executed molecular studies on the genus. On the other hand, no significant morphological synapomorphies for the recovered and well-supported infra-generic groups in the genus were reported by molecular studies. The importance of seed morphology in identification of species in Silene was emphasized in major taxonomic treatments of the genus, but a comprehensive study including a larger group of species is still lacking. This paper reports seed morphology of 42 species of genus Silene representing 22 sections distributed mainly in the area of Flora Iranica. The important characters and character states providing scorable variation were determined. Following seed characters are recognized to be valuable in determination of species and sections in Silene: general shape of the seeds, curvature of the seed lateral face, type of testa cells, development of the seed ridges, the cell surface; the shape of suture between adjacent cells and the state of the hilum. In addition, the phylogeny and current infra-generic classification of the genus is reviewed in light of data obtained from seed micromorphology. The species representing three sections, Conoimorphae, Melandriformes and Sclerocalycinae, show some degree of consistency in the seed features, while such uniformity could not be traced in other sections.