The pollen morphology of 16 species of aquatic angiosperms, distributed in 14 families from Karachi was examined by light and scanning microscope. Pollen grains are usually free, rarely united, mostly radially symmetrical, isopolar-apolar, occasionally-heteropolar. Simple aperturate (porate or colpate) pollen are more frequently found. Number of apertures varies from 1-3 or more than 30, rarely compound aperture as in Enhydra fluctuans Lour. Tectum of the families also is quite variable, ranging from reticulate to rugulate, striate, fossulate, echinate or scabrate/areolate. The pollen morphology of the families is significantly useful for characterizing the species. Apertural types and tectum types are the most significant pollen characters. On the basis of these characters 4 distinct pollen types are recognized.
PERVEEN, ANJUM (1999) "A Palynological Survey of Aquatic Flora of Karachi-Pakistan," Turkish Journal of Botany: Vol. 23: No. 5, Article 5. Available at: https://journals.tubitak.gov.tr/botany/vol23/iss5/5