Q.Explain pollen dimorphism as a floral adaptation, with reference to Viola or Commelina.

Some species, including Viola (violet) and Commelina (dayflower), produce two morphologically distinct kinds of flowers on the same plant: chasmogamous flowers, which open normally and expose their anthers and stigma to the environment (and hence to potential pollinators and cross-pollination), and cleistogamous flowers, which never open at all, so pollination happens necessarily and only by self-pollen within the still-closed bud.

This dual flower strategy is often accompanied by pollen dimorphism -- the pollen grains produced by the two flower types can differ, adapted to their very different pollination contexts (open exposure and possible cross-pollination vs. guaranteed enclosed self-pollination). The strategy gives the plant the best of both worlds: cleistogamous flowers reliably guarantee seed-set even without pollinators present, while chasmogamous flowers retain the possibility of genet …

Connect the two flower types (chasmogamous vs cleistogamous) each species produces to why their pollen might differ, and s …

Assuming cleistogamous flowers never produce seed because they never open -- in fact they guarantee self-pollination and …