Question

how stigma recognise the pollen of its own species

Answer 1

Commonly, the stigma is dilated on both sides and encircles the pollinium gradually, making it fall into its owncavity. In habitats that lack a pollinating agent, some speciesdevelop a structure that links with pistils and stamens to assist thepollen in reaching the stigma and achieving self-pollination

Answer 2

Pollination is the process that brings these male and female gametes together. Pollen can't get from the anthers to the ovules on its own, so pollination relies on other things to move the pollen. The wind or animals, especially insects and birds, pick up pollen from the male anthers and carry it to the female stigma.