Flower and Pollen Morphology Variations in Tilia spp. Populations in Hyrcanain Forests

Diversity in flower and pollen morphological traits was assessed in eight Iranian Tilia spp. populations. Flower samples were taken from 6 to 15 individuals in each population، with at least 100 m distance from each other. The results revealed that among the populations، the width of bract and peduncle had significant differences (p<0. 005)، but differences in length of bracts and pedicel were not significant. The lower altitude populations (<1200 m a. s. l) had longer pedicel than those of higher altitude ones (>1500 m a. s. l). Two style types including pubescence and glabrous style were recognized for the genus Tilia in these forest habitats. Pollen grain was medium size and oblate. Pollen of Hyrcanian،s Tilia has three very short oval furrows (except، some trees with 4 furrows in Asalem populations). There was a meaningful difference in the pollen sculpture of mountain populations (Bandbon and Dalir) compared to other populations. Also، only pubescence style and sparse stellate trichome were found on bracts of Bandbon population. In conclusion، polar and equatorial axes showed maximum variations and based on investigated traits، Bandbon population is different from other populations.