Page 28, XII NCERT

(a) The pollination that occurs in opened flowers is called chasmogamy. It is the most common type of pollination in all types of flowers. Chasmogamy is of two types i.e., self-pollination (autogamy) and cross-pollination. Cross-pollination is of two types /.e., geitonogamy and xenogamy.
So, we can say that chasmogamous flowers exhibit both autogamy (self-pollination) and allogamy (cross-pollination), While, in cleistogamous flower, the anthers and stigma lie close to each other within the closed flowers,
When anthers dehisce in the flower buds, pollen grains come in contact with the
stigma for effective pollination. Thus, these flowers are invariably autogamous as there
is no chance of cross-pollen landing on the stigma.