How does cleistogamy ensure autogamy?

(a) Cleistogamy is a type of self-pollination of certain flowers that can propagate by using non-opening, self-pollinating flowers. Cleistogamy ensures autogamy as cleistogamous flowers do not open at all and hence there is no chance of cross-pollination as there is no chance of cross-pollen landing on the stigma. (b) Advantage: Cleistogamous flowers produce assured seed set even in the absence of pollinators. Disadvantage: As there is no cross-pollination, there is no variation in the progeny.