Pollen morphology of 14 species of Abutilon and Hibiscus of the family Malvaceae (sensu stricto)

Pollen morphology and the degree of pollen variability within the fourteen species belonging to the two genera, Abutilon Mill. and Hibiscus L. of the family Malvaceae was studied and documented in detail using light microscopy (LM) and scanning electron microscopy (SEM). Two distinct pollen types were recognized based on polarity, shape, diameter and spine index of the pollen grains. The genus, Hibiscus is characterized by apolar, pantoporate and globose to spheroidal pollen grains whereas Abutilon is delimited by isopolar, 3-zonoporate and suboblate-spheroidal pollen grains. The wall of a mature pollen was composed of unremitting intine and exine overspread with spines of variable width and height. The character of spine index was used for the first time to describe Malvaceous pollen and was found to be of significant taxonomic importance.