Chasmogamous flowers are the flowers having open and exposed stigma and anther.
In order to facilitate pollination, they have scent and nectar to attract the pollinators.
Hibiscus, Sunflower, Peas are the examples of plants chasmogamous flowers.
on the other hand:
Cleistogamous flowers are closed flowers.
They don’t need pollinator for pollination.
Seed set is ensured in these flowers.
Cross pollination is absent, only self pollination takes place, as they always remain in bud stage.
Examples are Oxalis and Commelina. Chasmogamous flowers have exposed stigma amd anther while cleistogamous flowers never opens and always remains in bud stage.
