Implication of light and scanning electron microscopy for pollen morphology of selected taxa of family Asteraceae and Brassicaceae.

The present study was intended to assess pollen morphological attributes of selected Asteraceous and Brassicaceous species from tehsil Esa Khel (Mianwali), Punjab using scanning electron microscopy (SEM) and light microscopy (LM) techniques for its systematic and taxonomic significance for correct identification. Pollen from 12 different species belongs to two plant families from various distributional localities were collected, acetolyzed and measured. Different palynomorphological features were investigated using LM and SEM techniques. In Asteraceous species, three types of pollen (tricolporate, trizonocolporate, and tetracolporate) were observed. Pollen shape was observed prolate-spheroidal in three species while oblate and oblate-spheroidal were detected in Parthenium hysterophorus and Erigeron bonariensis. While sculpturing pattern of exine were echinate, echinate fenestrate, echinate perforate and scabrate echinate. Mesocolpium measurement was calculated maximum for Sonchus oleraceous (16.6 μm). Brassicaceae pollen were circular, lobate, tricolpate and exine show reticulate peculiarities. Whereas dominant shape was oblate-spheroidal followed by prolate-spheroidal and sub-prolate in Lepidium didymum and Sisymbrium irio, respectively. Mesocolpium distance was noted highest in Raphanus raphanistrum (14.4 μm). Exine thickness was noted maximum in Erigeron bonariensis (2.9 μm) in Asteraceous species and in Brassicaceae; Lepedium didymum exine measurement was 2.7 μm. The study showed that pollen micromorphology has important role to accurately identify and classify diverse plants genera belong to different families. Based on these taxonomic palynomorph features, the accurate identification of species from flora of tehsil Esa Khel, Mianwali were elaborated.