(a) : Cleistogamy is the process of pollination and fertilization before the flower has opened. In such flowers, the anther and stigma lie close to each other. When anthers dehisce in the flower buds, pollen grains come in contact with the stigma to effect pollination. Thus, cleistogamous flowers are invariably autogamous as there is no chance of cross­pollen landing on the stigma. Cleistogamous flowers produce assured seed­set even in the absence of pollinators.