Morphological and micromorphological studies of the new record Cerastium (Caryophyllaceae) from Iran

Genus Cerastium belongs to the subfamily Alsinoideae. This genus is represented with about 30 species in two subgenera (subgenus Dichodon and subgenus Cerastium) and three sections (sect. Strephodon، sect. Orthodon and sect. Schizodon) in flora Iranica area، of which 19 species were reported from Iran. The materials in the TARI herbarium were studied. The vegetative and reproductive characteristics of specimens were checked by stereomicroscope. In family Caryophyllaceae، the seeds bear numerous characters which can be used for taxonomic purposes. The ornamentation features of the seed surface and its relief are different from one species to another. The seeds were carefully taken from mature and dehiscent capsules. Pollen grains obtained from flowers bearing mature anthers. In this paper، Cerastium pentandrum (Caryophyllaceae) is reported as a new record from northwest Iran and Iranian plateau. It belongs to the subg. Cerastium sect. Orthodon. In this section teeth of the capsule are elongated، straight or reflexed، with flat or recurved margins. Morphological characteristics of the new record are provided. This taxon is compared with its closest relative C. balearicum. The ultrastructure of seed and pollen is examined by SEM.