A bisexual flower which normally open is called chasmogamous flower.
Kinds of Pollination
1. Autogamy: In this type, pollination is achieved within the same flower. Transfer of pollen grain from the anther to the stigma of the same flower. In a normal flower which opens and exposes the anthers and stigma complete autogamy is rather rare.
Majority of flowering plants produce hermaphrodite flowers and pollen grains are likely to come in contact with the stigma of the same flower. Continued self-pollination result in inbreeding depression. Flowering plants have developed many devices to discourage self-pollination and to encourage cross-pollination.
2. Geitonogamy: Transfer of pollen grains from the anther to the stigma of another flower of the same plant.
3. Xenogamy: Transfer of pollen grains from anther to the stigma of a different plant.