THE ANATOMICAL an‎d MICROMORPHOLOGICAL CHARACTERISTICS OF THYMUS PERSICUS (LAMIACEAE)

Thymus persicus is an endemic wild species of the genus Thymus in the Lamiaceae, grows in the northwest of Iran. In this research micromorphological feature of trichome, nutlet and pollen grain using light and scanning electron microscopes and anatomical characteristics was performed to evaluate taxonomic implication of these data. The leaf was dorsi-ventral in transverse section, including a one-layered epidermis, 2-3 layers of compact palisade parenchymatous cells, a large median vascular bundle whit one medium-sized and one small vascular bundle in both side of the mesophyll. Vascular bundle cap was found to be dense sclerenchymatous fibre on the phloem side. Bundle sheath was composed of one-layered parenchymatous cells. Indumentum includes a one to five-celled short and long eglandular trichomes, while glandular trichomes were of capitate and rarely peltate types. Stem had a single layer of epidermis covered with a cuticle as well as glandular and non-glandular trichomes and vascular bundles were separated by parenchymatous cells. Nutlets were 0.7 1.0 mm, brown, ovate in outline, glabrous and with star-shaped papillae ornamentation. The pollens were hexacolpate, isopolar and reticulate. The polar axis (P) and equatorial axis (E) of pollen were 37.4-40.4 and 24.8-28.1 µm, respectively. The ratio of P/E was found to be 1.3-1.5. The results showed that the leaf anatomical, nutlet and pollen micromorphological characteristics could be considered as taxonomic characters in species identification and circumscription of the genus Thymus.