Sexual Reproduction In Flowering Plants — BIOLOGY STD 12 Science — Question

→ In this type, pollination is achieved within the same flower. Transfer of pollen grains from the anther to the stigma of the same flower.
→ In a normal flower which opens and exposes the anthers and the stigma, complete autogamy is rather rare.
→ Autogamy in such flowers requires synchrony in pollen release and stigma receptivity and also, the anthers and the stigma should lie close to each other so that self-pollination can occur.
→ Some plants such as Viola (common pansy), Oxalis, and Commelina produce two types of flowers
→ Chasmogamous flowers which are similar to flowers of other species with exposed anthers and stigma (like a normal flower), and
→ Cleistogamous flowers which do not open at all.
→ In such flowers, the anthers 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 cross- pollen landing on the stigma.
→ Cleistogamous flowers produce assured seed-set even in the absence of pollinators.