Palynological investigation of selected species of family asteraceae using light and scanning electron microscopic techniques.

Palynological study on 11 species of family asteraceae, that is, Sonchus asper L., Gazania rigens L., Helianthus annus L., Dahlia pinnata Cav., Zinnia peruviana L., Tagetes erectus L., Glebionis coronaria L., Calendula officinale L., Osteospermum ecklonis L., Centaurea cyanus L. and Cosmos sulphureus Cav. was carried out in Islamia College University Campus. The light microscopy showed that pollens were oblate-sheroidal (C. cyanus), oblate (Z. peruviana), prolate-spheroidal (H. annuus, T. erectus, G. coronaria, C. officinale, O. ecklonis, C. sulphureus) and spheroidal (S. asper, G. rigens, D. pinnata) in shape. The pollen was trizonocolporate, tricolporate and echinolophate type, all pollens had echinate ornamentation except G. regins which had reticulate ornamentation under SEM. Maximum Pollens were isopolar and asymmetrical while some were apolar and radially symmetric. The P/E ratio was larger in G. rigens (45/47 µm), T. erectus (45/40 µm) and C. officinale (40/45 µm) while others had smaller P/E diameter. C. sulphureus had 6 µm thick exine when compared to other taxa. The larger number of spines/echini were found on the exine surface of H. annuus and S. asper and the distance between adjacent echini were 4-5 µm in C. cyanus and G. rigens than others which had distance equal to 1-3 µm, while pores were visible on pollen surface of C. cyanus, O. ecklonis, Z. peruviana, H. annuus and G. rigens under light microscope and were invisible on other pollen surfaces. The pollen of family asteraceae members was of stenopalynous type.