The underlying as- sumption is that larger pollen grains contain more nutrients than smaller ones, at least those that store starch, and this allows their pollen tubes to grow through deep stigmas that can not be traversed by pollen tubes from small pollen grains. Pollen number and duration of stigma receptivity.
A flower has more pollen grains than it does ovules so that the pollen has a better chance of getting to the ovules so they can make seeds so more plants will grow.
Explanation:
I think what you were trying to ask was Why does a flower have more pollen grains than it does ovules?
