Chasmogamy refers to the pollination of chasmogamous flowers. Flowers with exposed anthers and stigma are referred to as chasmogamous flowers. Most chasmogamous flowers are cross-pollinated by various pollinating agents such as wind, bees, insects, etc.
Chasmogamous flowers open to expose their reproductive parts (anther, stigma), thus allowing cross-pollination. Chasmogamous flowers are the opposite of cleistogamous flowers, which do not open at all. Cleistogamous flowers exclusively show self-fertilisation or autogamy.
Cross-pollination in chasmogamous flowers is beneficial as it leads to more genetic variability and reduces inbreeding depression. Cross-fertilisation produces more genetic diversity in seeds. Seeds produced by cross-fertilisation in chasmogamous flowers show increased fitness and hybrid vigour.
Chasmogamous flowers have attractive petals or nectaries to attract and reward pollinating agents and to promote cross-pollination. It is beneficial but there is a dependency on pollinating agents unlike cleistogamous flowers, which do not depend on pollinating agents for pollination and produce an assured seed-set.
Some plants produce both chasmogamous and cleistogamous flowers, e.g. Commelina, Viola, Oxalis, etc. The presence of both types of flowers allows both self-fertilisation and cross-fertilisation. It ensures genetic diversity along with the production of seeds in variable environments and less dependency on pollinators.
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