Question

How does the pollen in which stigma it should develop? Or can it develop in any stigma i.e., even the stigma of a flower of another species?

Answer 1

Each stigma has specific chemical receptors. Only when the pollen from the same species fall onto it, the receptors interact with the chemicals on the pollen cover. This leads to dissolution and development of a tract from the stigma through the style into the ovary which carries the pollen.