Features that aid pollination
FEATURES THAT AID SELF POLLINATION
Self-pollinated flowers are bisexual with the anthers and stigmas maturing at the same time.
Anthers are higher than stigma so that a visiting insect can brush the pollen grains into the stigma.
Sometimes, anthers and stigmas make direct contact as in Alamanda. In sun flower the stigmas at maturity cool back to make contact with the anthers if cross pollination fails to take place.
Some flowers never open until self-pollination has taken place. Examples are groundnut and cowpea.
Plants that undergo self-pollination are:
FEATURES THAT AID CROSS-POLLINATION
These are flowers with only one sexual reproductive organ, that is the male and female reproductive organ are in two different flowers. Unisexual flowers occur in maize, palm trees, pawpaw, pumpkin and Christmas bush.
This is the maturation of stamen and stigma of a bisexual flower at different times.
Self-sterility and self-incompatibility
This is a situation in which pollen grains of a flower or of another flower on the same plant will not result in fertilization even if they reach the stigma they are incompatible.