Abstract:
Pollen of 34 aquatic plants distributed in 13 dicotyledonous and 7 monocotyledonous families of Punjab (Pakistan) have been investigated by Light and Scanning Electron Microscopy. Pollen are generally free in most of the aquatic plants, rarely united in tetrads such as in Juncaceae and Typhaceae. Most of the pollen are radially symmetrical, isopolar-apolar, often heteropolar as in Trapa bispinosa Roxb., Nymphaea alba L., Eichhornia crassipes (Mart.) Roxb., Cyperus species, oblate-prolate spheroidal, infrequently prolate-subprolate. Non aperturate, poroid (false apertures), both simple (porate and colpate) and compound (colporate) apertures have been observed. Aquatic families also exhibit a great variation in tectum types varying from scabrate, reticulate to rugulate, verrucate, echinate, striate, sub-psilate punctuate, finely reticulate with muri patterns, areolate and scabrate-areolate punctate. The pollen characteristics are quite distinct for the identification of species. Five distinct types are recognized on the basis of tectum and apertural types i.e., Non-aperturate, Porate, Colpate, Colporate and Miscellaneous.
